a(1) = 1, n>1: a(n) = smallest m<>n and not occurring earlier such that m has as many prime-factors as n has (with repetition).
1, 3, 2, 6, 7, 4, 5, 12, 10, 9, 13, 8, 11, 15, 14, 24, 19, 20, 17, 18, 22, 21, 29, 16, 26, 25
2 seqfan posts
Wed Apr 8 00:55:37 CEST 2009 [seqfan] Re: Symmetric Relations and Self-Inverse Permutations