Don Reble writes: <<

And it scarcely seems credible that the next number would be 67,

Generating a bunch of random boolean 8x8's, I've gotten every determinant from 0 to 32, and 34, 35, 36, 42. 73 different values, when you count the negative ones. Sorry to Dan and Mr. Heegner.

...

Hey, that would be great -- another prime. --Dan