a(n) is the smallest number not yet in the sequence with the same number of distinct prime divisors as n, but relatively prime to n.
1, 3, 2, 5, 4, 35, 8, 7, 11, 21, 9, 55, 16, 15, 14, 13, 19, 65, 17, 33, 10, 39, 25, 77, 23
2 seqfan posts
Mon Apr 27 20:16:44 CEST 2009 [seqfan] Re: Symmetric Relations and Self-Inverse Permutations