n! + 1 is prime for 1, 2, 3, 11, 27, 37, 41, 73, 77, 116, 154, 320, 340,
399, 427, 872, 1477.  Search limit 4376.

n! - 1 is prime for 3, 4, 6, 7, 12, 14, 30, 32, 33, 38, 94, 116, 324,
379, 469, 546, 974, 1963, 3507.  Search limit 3533.