Pencilmark only Sudoku
Re: Pencilmark only Sudoku
by tarek » Wed Mar 19, 2014 9:16 pm
I use 1 line per puzzle. 729 characters per puzzle. An eliminated candidate would be a 0 or a ".". When I have time I'll post the last puzzle as a demonstration.
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tarek - Posts: 3762
- Joined: 05 January 2006
Re: Pencilmark only Sudoku
by tarek » Thu Mar 20, 2014 12:04 am
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tarek - Posts: 3762
- Joined: 05 January 2006
Re: Pencilmark only Sudoku
by 999_Springs » Thu Mar 20, 2014 12:06 am
i just constructed a nine-backdoor pencilmark only sudoku by hand
and i'm not going to tell you how i did it
and i'm not going to tell you how i did it
- 999_Springs
- Posts: 591
- Joined: 27 January 2007
- Location: In the toilet, flushing down springs, one by one.
Re: Pencilmark only Sudoku
by Smythe Dakota » Fri Mar 21, 2014 4:03 am
Must be the old alt-255 trick again.
Bill Smythe
Bill Smythe
- Smythe Dakota
- Posts: 564
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Re: Pencilmark only Sudoku
by 999_Springs » Fri Mar 21, 2014 6:14 pm
no really i mean it. what, you think i'm lying? i find your lack of faith disturbing.
- 999_Springs
- Posts: 591
- Joined: 27 January 2007
- Location: In the toilet, flushing down springs, one by one.
Easy Symmetric Pencilmark only Sudoku
by tarek » Sat Mar 22, 2014 9:40 pm
Symmetric & Easy Pencilmark only sudokus (sukakus)
Easy #01
Easy #02
Easy #03
Easy #01
Easy #02
Easy #03
Last edited by tarek on Thu Dec 19, 2019 6:19 pm, edited 1 time in total.
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tarek - Posts: 3762
- Joined: 05 January 2006
Re: Pencilmark only Sudoku
by 999_Springs » Sat Mar 22, 2014 10:19 pm
in contrast to tarek's "symmetric and easy" ones, here's an asymmetric hard one
looking for a 4x4 se 8+ now, closest i've found is an 8.2/8.2/6.6 that has 2 solutions that differ in 7 cells
still keeping the nine-backdoor pencilmark sudoku a secret
- Code: Select all
1234 134 | 1234 34
12 1234 | 1234 1234
----------+----------
234 134 | 234 1234
1234 1234 | 1234 23 ED=7.3/7.3/6.6
looking for a 4x4 se 8+ now, closest i've found is an 8.2/8.2/6.6 that has 2 solutions that differ in 7 cells
still keeping the nine-backdoor pencilmark sudoku a secret
- 999_Springs
- Posts: 591
- Joined: 27 January 2007
- Location: In the toilet, flushing down springs, one by one.
Re: Pencilmark only Sudoku
by 999_Springs » Tue Mar 25, 2014 9:08 pm
- Code: Select all
12 1234 | 1234 1234
1234 124 | 1234 34
----------+----------
1234 1234 | 14 1234
23 1234 | 1234 1234 ED=8.3/8.3/7.1
who knew 4x4 sudokus could ever be so hard?
i have no clue whether anybody's still following this thread or if i'm talking to myself here. so to find it out, if anyone wants the nine-backdoor pencilmark sudoku, please reply below with the following message:
"I hereby pledge that, on manifestation of a valid nine-backdoor pencilmark sudoku by 999_Springs, that I will set up a shrine to the omniscient 999_Springs and eternally worship, idolise, and bow before him"
- 999_Springs
- Posts: 591
- Joined: 27 January 2007
- Location: In the toilet, flushing down springs, one by one.
by Pat » Thu Mar 27, 2014 8:51 am
tarek (2014.Mar.20) wrote:
123456789.23456789.23456789.23456789.23456789.23456789.234567891234567891234567891234567891.34567891.34567891.34567891234567891.34567891.345678912345678912345678912...678912...678912345678912...678912.4.678912.45678912.4.678912...678912...678912.45678912.45678912345678912.45678912.45678912.45678912.45678912.4567891234567891.3.567891.3.567891.3.567891.3.567891.3.567891.3.567891.34567891.3.56789123456789123456789.23456.89.2345..89.23456789.2345..89.23456.89.2345..89.2345.789.2345..89123.567.9123.567.91234567.9123.567.91234567.91234567.91234567891234567.9123.567.912.4.678912.4567891234.678912.4.678912345678912.45678912.45678912.4.67891234.6789123456.891.3456.891.3456.891.3456.89123456.891.3456.891.3456.89123456789123456.89
the software at dailysudoku.com
accepts the colon (":") as the
separator between cells — [ play ]
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Pat - Posts: 4056
- Joined: 18 July 2005
Re:
by tarek » Thu Mar 27, 2014 4:08 pm
Pat wrote:tarek (2014.Mar.20) wrote:
123456789.23456789.23456789.23456789.23456789.23456789.234567891234567891234567891234567891.34567891.34567891.34567891234567891.34567891.345678912345678912345678912...678912...678912345678912...678912.4.678912.45678912.4.678912...678912...678912.45678912.45678912345678912.45678912.45678912.45678912.45678912.4567891234567891.3.567891.3.567891.3.567891.3.567891.3.567891.3.567891.34567891.3.56789123456789123456789.23456.89.2345..89.23456789.2345..89.23456.89.2345..89.2345.789.2345..89123.567.9123.567.91234567.9123.567.91234567.91234567.91234567891234567.9123.567.912.4.678912.4567891234.678912.4.678912345678912.45678912.45678912.4.67891234.6789123456.891.3456.891.3456.891.3456.89123456.891.3456.891.3456.89123456789123456.89
the software at dailysudoku.com
accepts the colon (":") as the
separator between cells — [ play ]
That is great. Although not my preferred way, it provides a line representation with less bits per line. I'm not sure how many electronic solvers support it. The pencilmark grid is supported IIRC by gsf's sudoku, SudoCue and JSudoku but that is not 1 puzzle per line representation.
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tarek - Posts: 3762
- Joined: 05 January 2006
Re: Singles backdoor size 6
by tarek » Tue Apr 15, 2014 8:44 am
Minimal singles backdoor size 6 puzzles
These were Minimal puzzles created from the same seed puzzle (So all share the same solution). That seed puzzle was special in that gsf's Sudoku confirmed that it has a singles backdoor size 5 and an FNBTHWXYKO backdoor size of 4.
I could not confirm how big the FNBTHWXYKO backdoor size for the minimal forms as it took forever on my limited hardware but they will all be >=4. All should have a Singles backdoor size 6. So IMO these are the most difficult Sudoku puzzles EVER posted to date in the FNBTHWXYKO world
.
To the purists who need the cells to have more than 1 candidate, I've modified these puzzles to another minimal form which shares the same singles outcome:
Here are the original 11 puzzles in the 729 line format
These were Minimal puzzles created from the same seed puzzle (So all share the same solution). That seed puzzle was special in that gsf's Sudoku confirmed that it has a singles backdoor size 5 and an FNBTHWXYKO backdoor size of 4.
I could not confirm how big the FNBTHWXYKO backdoor size for the minimal forms as it took forever on my limited hardware but they will all be >=4. All should have a Singles backdoor size 6. So IMO these are the most difficult Sudoku puzzles EVER posted to date in the FNBTHWXYKO world
.- Code: Select all
.-----------------------------------------------------------------------------------------------.
| 35678 13456789 123456789 | 23456789 46789 12456789 | 123456789 13456789 145789 |
| 12356789 137 123457 | 12389 12346789 1248 | 123689 1 12345789 |
| 123456789 1234567 12345678 | 12345689 123456789 12345678 | 1235689 1234569 123456789 |
:-----------------------------------------------------------------------------------------------:
| 23456789 46789 12456789 | 1356789 13456789 145789 | 23456789 146789 12456789 |
| 23689 12346789 123456789 | 12356789 1379 12345789 | 12356789 12346789 12478 |
| 12345689 12346 123456789 | 123569 12345679 12347 | 12345689 12346 12345678 |
:-----------------------------------------------------------------------------------------------:
| 123456789 156789 12456789 | 123456789 12345678 1245678 | 2356789 13456789 123456789 |
| 12356789 179 1245789 | 123689 12346789 12478 | 2356789 1379 12345789 |
| 123569 12345679 123456789 | 12345689 12346 12345678 | 123456789 12345679 123457 |
:-----------------------------------------------------------------------------------------------:
.-----------------------------------------------------------------------------------------------.
| 35678 13456789 123456789 | 23456789 46789 12456789 | 123456789 13456789 145789 |
| 123456789 137 123478 | 123689 12346789 1248 | 123689 1 12345789 |
| 123456789 1234567 12345678 | 12345689 23456789 12345678 | 1235689 1234569 123456789 |
:-----------------------------------------------------------------------------------------------:
| 23456789 46789 12456789 | 356789 13456789 145789 | 23456789 146789 12456789 |
| 123689 12346789 123456789 | 12356789 1379 12345789 | 12356789 12346789 12478 |
| 12345689 12346 12345678 | 123569 12345679 12347 | 123456789 12346 12345678 |
:-----------------------------------------------------------------------------------------------:
| 123456789 156789 12456789 | 23456789 12345678 1245678 | 2356789 13456789 123456789 |
| 12356789 179 12456789 | 23689 12346789 12478 | 2356789 1379 12345789 |
| 123569 12345679 123456789 | 12345689 12346 12345678 | 123456789 12345679 123457 |
:-----------------------------------------------------------------------------------------------:
.-----------------------------------------------------------------------------------------------.
| 35678 13456789 123456789 | 23456789 46789 12456789 | 123456789 13456789 145789 |
| 12356789 137 1234578 | 12389 12346789 12478 | 123689 1 12345789 |
| 123456789 1234567 12345678 | 12345689 23456789 12345678 | 1235689 1234569 123456789 |
:-----------------------------------------------------------------------------------------------:
| 23456789 146789 12456789 | 356789 13456789 145789 | 23456789 146789 12456789 |
| 23689 12346789 123456789 | 12356789 1379 12345789 | 12356789 12346789 12478 |
| 12345689 12346 123456789 | 123569 12345679 12347 | 12345689 12346 12345678 |
:-----------------------------------------------------------------------------------------------:
| 123456789 156789 12456789 | 123456789 12345678 1245678 | 2356789 13456789 123456789 |
| 12356789 179 1245789 | 23689 12346789 12478 | 2356789 1379 12345789 |
| 123569 12345679 123456789 | 12345689 12346 12345678 | 123456789 12345679 123457 |
:-----------------------------------------------------------------------------------------------:
.-----------------------------------------------------------------------------------------------.
| 35678 13456789 123456789 | 23456789 46789 12456789 | 123456789 13456789 145789 |
| 123456789 137 12347 | 1289 1234689 1248 | 123689 1 12345789 |
| 123456789 1234567 12345678 | 12345689 123456789 123456789 | 1235689 12345689 123456789 |
:-----------------------------------------------------------------------------------------------:
| 23456789 146789 12456789 | 356789 13456789 145789 | 23456789 146789 12456789 |
| 23689 12346789 123456789 | 12356789 1379 12345789 | 12356789 12346789 12478 |
| 12345689 12346 123456789 | 123569 12345679 123457 | 12345689 12346 12345678 |
:-----------------------------------------------------------------------------------------------:
| 123456789 156789 12456789 | 23456789 12345678 1245678 | 2356789 13456789 123456789 |
| 12356789 179 1245789 | 23689 12346789 12478 | 2356789 1379 12345789 |
| 1235689 12345679 123456789 | 12345689 12346 12345678 | 123456789 12345679 123457 |
:-----------------------------------------------------------------------------------------------:
.-----------------------------------------------------------------------------------------------.
| 345678 13456789 123456789 | 23456789 46789 12456789 | 123456789 13456789 145789 |
| 123456789 137 1347 | 123689 12346789 12478 | 123689 1 12345789 |
| 123456789 1234567 12345678 | 12345689 123456789 12345678 | 1235689 12345689 123456789 |
:-----------------------------------------------------------------------------------------------:
| 23456789 46789 12456789 | 356789 13456789 145789 | 23456789 146789 12456789 |
| 23689 12346789 123456789 | 12356789 1379 12345789 | 12356789 12346789 12478 |
| 12345689 12346 123456789 | 123569 12345679 123457 | 12345689 12346 12345678 |
:-----------------------------------------------------------------------------------------------:
| 123456789 156789 12456789 | 123456789 12345678 1245678 | 2356789 13456789 123456789 |
| 12356789 179 1245789 | 23689 12346789 12478 | 2356789 1379 12345789 |
| 123569 12345679 123456789 | 12345689 12346 12345678 | 123456789 12345679 123457 |
:-----------------------------------------------------------------------------------------------:
.-----------------------------------------------------------------------------------------------.
| 356789 13456789 123456789 | 23456789 46789 12456789 | 123456789 13456789 145789 |
| 12356789 137 123457 | 123689 12346789 12478 | 123689 1 12345789 |
| 123456789 1234567 12345678 | 12345689 12456789 12345678 | 1235689 12345689 123456789 |
:-----------------------------------------------------------------------------------------------:
| 23456789 46789 12456789 | 1356789 13456789 145789 | 23456789 146789 12456789 |
| 23689 12346789 123456789 | 12356789 1379 12345789 | 12356789 12346789 12478 |
| 12345689 12346 123456789 | 123569 12345679 12347 | 12345689 12346 12345678 |
:-----------------------------------------------------------------------------------------------:
| 123456789 156789 12456789 | 123456789 12345678 1245678 | 2356789 13456789 123456789 |
| 12356789 179 1245789 | 23689 12346789 12478 | 2356789 1379 12345789 |
| 123569 12345679 123456789 | 12345689 12346 12345678 | 123456789 12345679 123457 |
:-----------------------------------------------------------------------------------------------:
.-----------------------------------------------------------------------------------------------.
| 356789 13456789 123456789 | 23456789 46789 12456789 | 123456789 13456789 145789 |
| 12356789 137 123457 | 123689 12346789 12478 | 123689 1 12345789 |
| 123456789 1234567 12345678 | 12345689 12456789 12345678 | 1235689 1234569 123456789 |
:-----------------------------------------------------------------------------------------------:
| 23456789 46789 12456789 | 1356789 13456789 145789 | 23456789 146789 12456789 |
| 23689 12346789 123456789 | 12356789 1379 12345789 | 12356789 12346789 12478 |
| 12345689 12346 12345678 | 123569 12345679 12347 | 123456789 12346 12345678 |
:-----------------------------------------------------------------------------------------------:
| 123456789 156789 12456789 | 123456789 12345678 1245678 | 2356789 13456789 123456789 |
| 12356789 179 1245789 | 123689 12346789 12478 | 2356789 1379 12345789 |
| 123569 12345679 123456789 | 12345689 12346 12345678 | 123456789 12345679 123457 |
:-----------------------------------------------------------------------------------------------:
.-----------------------------------------------------------------------------------------------.
| 356789 13456789 123456789 | 23456789 46789 12456789 | 123456789 13456789 145789 |
| 12356789 137 12345678 | 123689 12346789 12478 | 123689 1 12345789 |
| 123456789 1234567 12345678 | 12345689 23456789 12345678 | 1235689 1234569 123456789 |
:-----------------------------------------------------------------------------------------------:
| 23456789 46789 12456789 | 356789 13456789 145789 | 23456789 146789 12456789 |
| 23689 12346789 123456789 | 12356789 1379 12345789 | 12356789 12346789 12478 |
| 12345689 12346 123456789 | 123569 12345679 123457 | 12345689 12346 12345678 |
:-----------------------------------------------------------------------------------------------:
| 123456789 156789 12456789 | 123456789 12345678 1245678 | 2356789 13456789 123456789 |
| 12356789 179 1245789 | 23689 12346789 12478 | 2356789 1379 12345789 |
| 123569 12345679 123456789 | 12345689 12346 12345678 | 123456789 12345679 123457 |
:-----------------------------------------------------------------------------------------------:
.-----------------------------------------------------------------------------------------------.
| 35678 13456789 123456789 | 23456789 46789 12456789 | 123456789 13456789 145789 |
| 12356789 137 123457 | 123689 12346789 12478 | 1235689 1 12345789 |
| 123456789 1234567 12345678 | 12345689 123456789 12345678 | 1235689 12345689 123456789 |
:-----------------------------------------------------------------------------------------------:
| 23456789 46789 12456789 | 356789 13456789 145789 | 23456789 146789 12456789 |
| 23689 12346789 123456789 | 12356789 1379 12345789 | 12356789 12346789 12478 |
| 12345689 12346 12345678 | 123569 12345679 123457 | 123456789 12346 12345678 |
:-----------------------------------------------------------------------------------------------:
| 123456789 156789 12456789 | 123456789 12345678 1245678 | 2356789 13456789 123456789 |
| 12356789 179 1245789 | 23689 12346789 12478 | 2356789 1379 12345789 |
| 123569 12345679 123456789 | 12345689 12346 12345678 | 123456789 12345679 123457 |
:-----------------------------------------------------------------------------------------------:
.-----------------------------------------------------------------------------------------------.
| 356789 13456789 123456789 | 23456789 46789 12456789 | 123456789 13456789 145789 |
| 12356789 137 123457 | 12689 12346789 1248 | 1235689 1 12345789 |
| 123456789 1234567 12345678 | 12345689 123456789 12345678 | 1235689 12345689 123456789 |
:-----------------------------------------------------------------------------------------------:
| 23456789 46789 12456789 | 356789 13456789 145789 | 23456789 146789 12456789 |
| 23689 12346789 123456789 | 12356789 1379 12345789 | 12356789 12346789 12478 |
| 12345689 12346 12345678 | 123569 12345679 123457 | 123456789 12346 12345678 |
:-----------------------------------------------------------------------------------------------:
| 123456789 156789 12456789 | 123456789 12345678 1245678 | 2356789 13456789 123456789 |
| 12356789 179 1245789 | 123689 12346789 12478 | 2356789 1379 12345789 |
| 123569 12345679 123456789 | 12345689 12346 12345678 | 123456789 12345679 123457 |
:-----------------------------------------------------------------------------------------------:
.-----------------------------------------------------------------------------------------------.
| 356789 13456789 123456789 | 23456789 46789 12456789 | 123456789 13456789 145789 |
| 12356789 137 123457 | 123689 12346789 1248 | 123689 1 12345789 |
| 123456789 1234567 12345678 | 12345689 123456789 12345678 | 1235689 1234569 123456789 |
:-----------------------------------------------------------------------------------------------:
| 23456789 146789 12456789 | 1356789 13456789 145789 | 23456789 146789 12456789 |
| 23689 12346789 123456789 | 12356789 1379 12345789 | 12356789 12346789 12478 |
| 12345689 12346 12345678 | 123569 12345679 12347 | 123456789 12346 12345678 |
:-----------------------------------------------------------------------------------------------:
| 123456789 156789 12456789 | 123456789 12345678 1245678 | 2356789 13456789 123456789 |
| 12356789 179 1245789 | 123689 12346789 12478 | 2356789 1379 12345789 |
| 123569 12345679 123456789 | 12345689 12346 12345678 | 123456789 12345679 123457 |
:-----------------------------------------------------------------------------------------------:
To the purists who need the cells to have more than 1 candidate, I've modified these puzzles to another minimal form which shares the same singles outcome:
Hidden Text: Show
Here are the original 11 puzzles in the 729 line format
Hidden Text: Show
-
tarek - Posts: 3762
- Joined: 05 January 2006
Singles backdoor size 9
by 999_Springs » Tue Apr 15, 2014 2:51 pm
because the way tarek's last post was written clearly indicates he does not believe me when i tell him EVER SO VOCIFEROUSLY that there is a very easily found singles backdoor size NINE in the world of pencilmark sudoku i'll just post it here
so you start with the canonical grid
and then you regard that grid as a concatenation of nine 3x3 latin squares. easy enough right?
then you replace each 3x3 latin square with this (replace 1,2,3 with 4,5,6 or 7,8,9 as appropriate)
or this
to get a grid that looks something like this, which is what you'd get if you only used the first one:
voila
you may now bow down in eternal worship to me
so you start with the canonical grid
- Code: Select all
123|456|789
456|789|123
789|123|456
---+---+---
231|564|897
564|897|231
897|231|564
---+---+---
312|645|978
645|978|312
978|312|645
and then you regard that grid as a concatenation of nine 3x3 latin squares. easy enough right?
then you replace each 3x3 latin square with this (replace 1,2,3 with 4,5,6 or 7,8,9 as appropriate)
- Code: Select all
123 12 123
12 23 13
13 123 12
or this
- Code: Select all
1 23 23
23 13 12
23 12 123
to get a grid that looks something like this, which is what you'd get if you only used the first one:
- Code: Select all
123 12 123 |456 45 456 |789 78 789
456 45 456 |789 78 789 |123 12 123
789 78 789 |123 12 123 |456 45 456
--------------+--------------+-------------
12 23 13 |45 56 46 |78 89 79
45 56 46 |78 89 79 |12 23 13
78 89 79 |12 23 13 |45 56 46
--------------+--------------+-------------
13 123 12 |46 456 45 |79 789 78
46 456 45 |79 789 78 |13 123 12
79 789 78 |13 123 12 |46 456 45
voila
you may now bow down in eternal worship to me
- 999_Springs
- Posts: 591
- Joined: 27 January 2007
- Location: In the toilet, flushing down springs, one by one.
Re: Singles backdoor size 9
by blue » Fri Apr 18, 2014 5:29 pm
999_Springs wrote:
- Code: Select all
123 12 123 |456 45 456 |789 78 789
456 45 456 |789 78 789 |123 12 123
789 78 789 |123 12 123 |456 45 456
--------------+--------------+-------------
12 23 13 |45 56 46 |78 89 79
45 56 46 |78 89 79 |12 23 13
78 89 79 |12 23 13 |45 56 46
--------------+--------------+-------------
13 123 12 |46 456 45 |79 789 78
46 456 45 |79 789 78 |13 123 12
79 789 78 |13 123 12 |46 456 45
voila
Nine completely independent (3x3) puzzles, each with backdoor size of one. Very clever
- blue
- Posts: 1085
- Joined: 11 March 2013
Re: Singles backdoor size 9
by tarek » Fri Apr 18, 2014 10:21 pm
blue wrote:999_Springs wrote:
- Code: Select all
123 12 123 |456 45 456 |789 78 789
456 45 456 |789 78 789 |123 12 123
789 78 789 |123 12 123 |456 45 456
--------------+--------------+-------------
12 23 13 |45 56 46 |78 89 79
45 56 46 |78 89 79 |12 23 13
78 89 79 |12 23 13 |45 56 46
--------------+--------------+-------------
13 123 12 |46 456 45 |79 789 78
46 456 45 |79 789 78 |13 123 12
79 789 78 |13 123 12 |46 456 45
voila
Nine completely independent (3x3) puzzles, each with backdoor size of one. Very clever
Indeed well done. And that is your nine backdoors!!!
-
tarek - Posts: 3762
- Joined: 05 January 2006
637 candidates
by dobrichev » Tue Jul 09, 2019 7:50 am
This puzzle has 637 candidates.
Play it
It appears 13 years after Ruud's record of 633. It was found using JPF's seeds from 17s, then vicinity search.
- Code: Select all
+-------------------------------+-------------------------------+-------------------------------+
| 123456789 123456789 23456789 | 12346789 123456789 1246789 | 12346789 1234678 123456789 |
| 123456789 135 23567 | 2356789 123456789 123456789 | 123456789 237 123456789 |
| 123456789 123456789 123456789 | 1256789 123456789 1245789 | 123456789 12346789 123456789 |
+-------------------------------+-------------------------------+-------------------------------+
| 123456789 123456789 123456789 | 256789 123456789 123456789 | 123456789 123456789 123456789 |
| 123456789 14 123456789 | 1245789 123456789 123456789 | 45 123456789 123456789 |
| 123456789 123456789 123456789 | 12356789 123456789 123456789 | 123456789 123456789 123456789 |
+-------------------------------+-------------------------------+-------------------------------+
| 123456789 123456789 23456789 | 123456789 1234569 12346789 | 123456789 27 123456789 |
| 123456789 123456789 123456789 | 123456789 13459 1469 | 123456789 123456789 123456789 |
| 123456789 123456789 25 | 123456789 12345679 12345679 | 123456789 27 257 |
+-------------------------------+-------------------------------+-------------------------------+
Play it
It appears 13 years after Ruud's record of 633. It was found using JPF's seeds from 17s, then vicinity search.
- dobrichev
- 2016 Supporter
- Posts: 1879
- Joined: 24 May 2010
