[math-fun] Factoring near-factorials

So, I recently came across this: 4!+1 = 5^2 5!+1 = 11^2 7!+1 = 71^2 Is there any other n such that n!+1 is a perfect square? A perfect square of a prime? Also, n!+1 seems to generate a fair number of primes. For instance, 73!+1 appears to be prime. But this is apparently well known. -- -- http://cube20.org/ -- http://golly.sf.net/ --