Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #6 Mar 29 2017 20:29:16
%S 1,2,7,8,10,14,17,21,24,27,29,33,35,38,41,43,47,49,53,56,59,62,65,68,
%T 71,75,77,81,84,87,90,93,96,99,102,105,107,111,113,117,119,123,125,
%U 129,131,135
%N a(n) = c(n-1) + c(n-3) where c is the sequence of numbers not in a.
%H Ivan Neretin, <a href="/A022431/b022431.txt">Table of n, a(n) for n = 0..10000</a>
%t Fold[Append[#1, Plus @@ Complement[Range[Max@#1 + 3], #1][[{#2, #2 + 2}]]] &, {1, 2, 7}, Range[43]] (* _Ivan Neretin_, Mar 29 2017 *)
%Y Cf. A022424 and references therein.
%K nonn
%O 0,2
%A _Clark Kimberling_