A126091 a(1)=1;a(2)=4; for n>2, a(n)=a(n-2)+3 if n is already in the sequence, a(n)=a(n-2)+1 otherwise.

1, 4, 2, 7, 3, 8, 6, 11, 7, 12, 10, 15, 11, 16, 14, 19, 15, 20, 18, 23, 19, 24, 22, 27, 23, 28, 26, 31, 27, 32, 30, 35, 31, 36, 34, 39, 35, 40, 38, 43, 39, 44, 42, 47, 43, 48, 46, 51, 47, 52, 50, 55, 51, 56, 54, 59, 55, 60, 58, 63, 59, 64, 62, 67, 63, 68, 66, 71, 67, 72, 70, 75

Offset

1,2

Links

Table of n, a(n) for n=1..72.

Mathematica

a={1, 4}; Do[If[MemberQ[a, n], b=a[[n-2]]+3, b=a[[n-2]]+1]; AppendTo[a, b], {n, 3, 70}]; a

Crossrefs

Cf. A080578, A080455-A080458.

Sequence in context: A222622 A161179 A105727 * A026189 A026213 A319556

Adjacent sequences: A126088 A126089 A126090 * A126092 A126093 A126094

Keyword

nonn

Author

Zak Seidov, Mar 11 2007

Status

approved