A174836 a(n) = 1 + ((6*n-1)*2^n + (-1)^n)/3.

1, 4, 16, 46, 124, 310, 748, 1750, 4012, 9046, 20140, 44374, 96940, 210262, 453292, 972118, 2075308, 4412758, 9349804, 19748182, 41593516, 87381334, 183151276, 383079766, 799713964, 1666536790, 3467291308, 7203018070, 14942907052, 30959555926, 64066595500, 132428158294

Offset

0,2

Links

Table of n, a(n) for n=0..31.

Index entries for linear recurrences with constant coefficients, signature (4, -3, -4, 4).

Formula

G.f.: 1/(1-x) + 1/(3*(1+x)) - 1/(3*(1-2*x)) + 8*x/(1-2*x)^2. [Richard Choulet, Apr 04 2010]

a(n) = 3*A113861(n+1) + 1. - Michel Marcus, Feb 05 2019

Prog

(PARI) a(n) = 1 + ((6*n-1)*2^n+(-1)^n)/3; \\ Michel Marcus, Feb 05 2019

Crossrefs

Cf. A113861.

Sequence in context: A007315 A055342 A213292 * A244252 A369401 A308592

Adjacent sequences: A174833 A174834 A174835 * A174837 A174838 A174839

Keyword

nonn,easy

Author

Fernando J. Ballesteros (fernando.ballesteros(AT)uv.es), Mar 30 2010

Extensions

More terms from Michel Marcus, Feb 05 2019

Status

approved