A022437 a(n) = c(n-1) + c(n-3) where c is the sequence of numbers not in a.

2, 3, 4, 7, 13, 15, 18, 20, 22, 25, 28, 31, 35, 38, 42, 45, 49, 51, 55, 57, 61, 63, 66, 69, 71, 75, 77, 80, 83, 85, 89, 91, 94, 97, 100, 103, 106, 109, 112, 115, 118, 121, 124, 127, 131, 133

Offset: 0

Author

Clark Kimberling

Keywords

• nonn

Links

• Ivan Neretin, Table of n, a(n) for n = 0..10000

Crossrefs

Cf. A022424 and references therein.

Programs

Mathematica

Fold[Append[#1, Plus @@ Complement[Range[Max@#1 + 3], #1][[{#2, #2 + 2}]]] &, {2, 3, 4}, Range[43]] (* Ivan Neretin, Mar 30 2017 *)