Simple way to generate up to Take a Solved Sudoko puzzle,
step 1 ) replace all 1 with A , 2 with B till 9 with I,
Step 2) do a shuffle in each horizontal and vertical block block of using a random between 1 and 3, here in each there can only be 3 possible combinations.
step 3) now shuffle the block there can only be 3 vertical and 3 horizontal shuffle
step 4) rotate the block 1 to 4 time..
step 5) mirror the puzzle vertically and horizontally using a random between 1 and 2.
step 6) replace all A with any number 1 to 9..
guessing this will produce around 38,093,690,880 combos....