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[Fireball]

I looked up Fermat primes, and was saddened that 256^2 + 1 was not prime. Those kind of facts are why I dug into math as a kid. Now that I'm old, I've forgotten most of it.    Use it or lose it is so true.

Actually, 256^2 +1 =65537 *is* prime. The next one, 65536^2 +1 is not.

 I knew that, but I wrote 256^2 +1 instead of 65536^2 +1. I blame not being fully caffeinated.