A077822 Expansion of (1-x)^(-1)/(1-3*x-3*x^2-2*x^3).

1, 4, 16, 63, 246, 960, 3745, 14608, 56980, 222255, 866922, 3381492, 13189753, 51447580, 200674984, 782747199, 3053161710, 11909076696, 46452209617, 181190182360, 706745329324, 2756710954287, 10752749215554, 41941871168172, 163597283059753, 638122961114884

Offset: 0

Author

N. J. A. Sloane, Nov 17 2002

Keywords

• nonn
• easy

Links

• Index entries for linear recurrences with constant coefficients, signature (4,0,-1,-2).

Crossrefs

Cf. A077829 (first differences).

Programs

Mathematica

CoefficientList[Series[(1 - x)^(-1)/(1 - 3*x - 3*x^2 - 2*x^3), {x, 0, 30}], x] (* Wesley Ivan Hurt, Jan 20 2024 *)

Formula

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

a(n) = 4*a(n-1) - a(n-3) - 2*a(n-4). - Wesley Ivan Hurt, Jan 20 2024