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A022428
a(n) = c(n-1) + c(n-3) where c is the sequence of numbers not in a.
2
1, 2, 4, 9, 12, 14, 17, 19, 23, 26, 29, 33, 36, 39, 42, 45, 47, 51, 53, 57, 59, 62, 65, 67, 71, 73, 77, 79, 83, 85, 89, 92, 95, 98, 101, 104, 107, 110, 113, 116, 119, 123, 125, 129, 132, 135
OFFSET
0,2
LINKS
MATHEMATICA
Fold[Append[#1, Plus @@ Complement[Range[Max@#1 + 3], #1][[{#2, #2 + 2}]]] &, {1, 2, 4}, Range[43]] (* Ivan Neretin, Mar 29 2017 *)
CROSSREFS
Cf. A022424 and references therein.
Sequence in context: A096134 A058885 A256446 * A096186 A359817 A175041
KEYWORD
nonn
STATUS
approved