A066858 Smallest k>1 such that for each integer x, x^k=x or x^k=0 (mod n); or 0 if no such k exists.

2, 3, 3, 5, 3, 7, 3, 7, 5, 11, 0, 13, 7, 5, 5, 17, 0, 19, 0, 7, 11, 23, 0, 21, 13, 19, 0, 29, 5, 31, 9, 11, 17, 13, 0, 37, 19, 13, 0, 41, 7, 43, 0, 0, 23, 47, 0, 43, 0, 17, 0, 53, 0, 21, 0, 19, 29, 59, 0, 61, 31, 0, 17, 13, 11, 67, 0, 23, 13, 71, 0, 73, 37, 0, 0, 31, 13, 79, 0, 55, 41