The way I’m doing it is very “rustic” and based on Havard’s thread :

I pick two or three “home made” 19s and follow the sequence :

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`initial op. final number`

clues clues of puzzles

19

19 {-2+2}x p 19 N1

19 {-1+1}x q 19 N2

19 {-2+1} 18 N3

18 {-1+1}x r 18 N4

18 {-2+1} 17

p, q, r are small integers.

N1 and N2 depend a lot on the initial 19.

I adjust p, q, r in order to get N4=20000

Up to now, every run gave me at least one and up to 6 (luckily) new 17s.

With my labtop, it takes 24 hours for each run...

But I got 3 free 17s by doing an exhaustive {-1+1} on the Gordon’s list.

3 new 17s popped up ; each of them had a dual {-1+1} already in the list : one from Gordon, one from JPF, one from gsf

PS :

Gordon Royle wrote:Do you have a 17-clue Sudoku puzzle that might be new? Or is it just an isomorphic copy of one of the known ones?

Enter your puzzle here and we'll let you know if it's already in the database, or if it's a new one.

JPF