A077845 Expansion of (1-x)^(-1)/(1-2*x-2*x^2-x^3).

1, 3, 9, 26, 74, 210, 595, 1685, 4771, 13508, 38244, 108276, 306549, 867895, 2457165, 6956670, 19695566, 55761638, 157871079, 446961001, 1265425799, 3582644680, 10143101960, 28716919080, 81302686761, 230182313643, 651686919889, 1845041153826, 5223638461074

Offset

0,2

Links

Table of n, a(n) for n=0..28.

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

Formula

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

a(n) = 3*a(n-1)-a(n-3)-a(n-4). - Wesley Ivan Hurt, Mar 10 2015

Mathematica

CoefficientList[Series[(1 - x)^(-1)/(1 - 2*x - 2*x^2 - x^3), {x, 0, 30}], x] (* Wesley Ivan Hurt, Mar 10 2015 *)

Prog

(PARI) Vec(1/((1-x)*(1-2*x-2*x^2-x^3)) + O(x^30)) \\ Michel Marcus, Mar 10 2015

Crossrefs

Sequence in context: A268093 A127911 A116423 * A291000 A276068 A171277

Adjacent sequences: A077842 A077843 A077844 * A077846 A077847 A077848

Keyword

nonn,easy

Author

N. J. A. Sloane, Nov 17 2002

Status

approved