Reversing binary representation of n. Converting sum of powers of 2 in binary representation of a(n) to alternating sum gives n.
1, 2, 7, 4, 13, 14, 11, 8, 25, 26, 31, 28, 21, 22, 19, 16, 49, 50, 55, 52, 61, 62, 59, 56
1 seqfan posts
Sun Dec 20 18:57:27 CET 2009 [seqfan] Sturdy and flimsy numbers.