On Thu, 17 May 2012, Barry Callahan wrote: EXCEPT that that apparently treats two "symmetrical" (any/all rotations, etc.) ones as being distinct. There are about 3/10^7 different symmetry permutations. Does that reduce it to about 2 E 14 Burnside said 5E9

Thats a nice number but give no indication of how many unique single solution games can be created. One should be able to create more than one unique single solution game for each filled grid. That at least sets a lower limit on the total number. I wonder if that number is not including rotation of grid or swapping of the numbers. If it does, it would be a somewhat lower number but not so much that a lifetime of creating games would make a dent. Dwight