A100136 a(n) = Sum_{k=0..floor(n/6)} C(n-3k,3k) * 3^k.

1, 1, 1, 1, 1, 1, 4, 13, 31, 61, 106, 169, 262, 424, 748, 1417, 2749, 5251, 9709, 17395, 30553, 53434, 94285, 168859, 306283, 558742, 1017895, 1844044, 3320044, 5952472, 10660177, 19119385, 34383781, 61985497, 111884665, 201938701, 364128136

Offset

0,7

Links

Seiichi Manyama, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (3,-3,1,0,0,3).

Formula

G.f.: (1-x)^2/((1-x)^3 - 3x^6).

a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) + 3*a(n-6).

Crossrefs

Cf. A098576, A100134, A100135.

Sequence in context: A191189 A106302 A158842 * A097120 A098536 A216563

Adjacent sequences: A100133 A100134 A100135 * A100137 A100138 A100139

Keyword

easy,nonn

Author

Paul Barry, Nov 06 2004

Status

approved