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A022431
a(n) = c(n-1) + c(n-3) where c is the sequence of numbers not in a.
1
1, 2, 7, 8, 10, 14, 17, 21, 24, 27, 29, 33, 35, 38, 41, 43, 47, 49, 53, 56, 59, 62, 65, 68, 71, 75, 77, 81, 84, 87, 90, 93, 96, 99, 102, 105, 107, 111, 113, 117, 119, 123, 125, 129, 131, 135
OFFSET
0,2
LINKS
MATHEMATICA
Fold[Append[#1, Plus @@ Complement[Range[Max@#1 + 3], #1][[{#2, #2 + 2}]]] &, {1, 2, 7}, Range[43]] (* Ivan Neretin, Mar 29 2017 *)
CROSSREFS
Cf. A022424 and references therein.
Sequence in context: A168064 A243167 A039005 * A356671 A047525 A075766
KEYWORD
nonn
STATUS
approved