a(n)-1 in ternary = n-1 in binary; also: a(1) = 1, a(2) = 2, a(n) is smallest number k which avoids any 3-term arithmetic progression in a(1), a(2), ..., a(n-1), k.
1, 2, 4, 5, 10, 11, 13, 14, 28, 29, 31, 32, 37, 38, 40, 41, 82, 83, 85, 86, 91, 92, 94, 95
1 seqfan posts
Mon Nov 23 10:23:23 CET 2009 [seqfan] Re: a(a(n)) is a square