a(1) = 1; for n>1, a(n) = the smallest positive integer root of n not included earlier, if such a root exists, otherwise the smallest power of n not included earlier, subject to a(n)<>n.
1, 4, 9, 2, 25, 36, 49, 64, 3, 100, 121, 144, 169, 196, 225, 256, 289, 324, 361, 400
2 seqfan posts
Wed Apr 8 00:55:37 CEST 2009 [seqfan] Re: Symmetric Relations and Self-Inverse Permutations