A176812 Expansion of 3*(1+x)/(1-2*x-5*x^2).

3, 9, 33, 111, 387, 1329, 4593, 15831, 54627, 188409, 649953, 2241951, 7733667, 26677089, 92022513, 317430471, 1094973507, 3777099369, 13029066273, 44943629391, 155032590147, 534783327249, 1844729605233, 6363375846711

Offset

0,1

Comments

Binomial transform of A026532 after dropping A026532(0). - R. J. Mathar, Apr 27 2010

Links

Table of n, a(n) for n=0..23.

Index entries for linear recurrences with constant coefficients, signature (2,5).

Formula

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

a(n) = 3 * A180168(n).

Mathematica

CoefficientList[Series[(-3(1+x))/(5x^2+2x-1), {x, 0, 40}], x]  (* Harvey P. Dale, Feb 24 2011 *)

Crossrefs

Sequence in context: A343735 A037129 A148987 * A192430 A323790 A148988

Adjacent sequences: A176809 A176810 A176811 * A176813 A176814 A176815

Keyword

nonn,easy,less

Author

Roger L. Bagula, Apr 26 2010

Status

approved