A133453 a(n) = 3*a(n-1) - a(n-3) + 3*a(n-4).

2, 4, 13, 40, 122, 365, 1094, 3280, 9841, 29524, 88574, 265721, 797162, 2391484, 7174453, 21523360, 64570082, 193710245, 581130734, 1743392200, 5230176601, 15690529804, 47071589414, 141214768241, 423644304722, 1270932914164

Offset

0,1

Links

Table of n, a(n) for n=0..25.

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

Formula

O.g.f: -(2 - 2*x + x^2 + 3*x^3)/((3*x-1)*(x+1)*(x^2-x+1)). - R. J. Mathar, Nov 30 2007

6*a(n) = 3^(n+2) +(-1)^n +2*A057079(n+2). - R. J. Mathar, Oct 03 2021

Mathematica

LinearRecurrence[{3, 0, -1, 3}, {2, 4, 13, 40}, 30] (* Harvey P. Dale, Sep 10 2018 *)

Crossrefs

Cf. A129339.

Sequence in context: A093630 A033091 A282741 * A085422 A264630 A065601

Adjacent sequences: A133450 A133451 A133452 * A133454 A133455 A133456

Keyword

nonn,easy

Author

Paul Curtz, Nov 27 2007

Status

approved