I guess there must be a way to calculate this precisely in a reasonable time, but if you only want an approximate answer, that's much easier. Just use sampling.

I made the computer fill the board with random letters 10_000_000 times, and 896_728 out of those were correct (no three adjacent letters in a row or column). As there are 6.33e49 possible boards, this means there are approximately 5.68e48 correct boards.

In reply to Re: Pattern enumeration. by ambrus
in thread Pattern enumeration. by BrowserUk

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