A232231 G.f.: (1-3*x+2*x^2+2*x^4+4*x^5)/((1-x)*(1-3*x-4*x^3)).

1, 1, 3, 13, 45, 153, 517, 1737, 5829, 19561, 65637, 220233, 738949, 2479401, 8319141, 27913225, 93657285, 314248425, 1054398181, 3537823689, 11870464773, 39828987049, 133638255909, 448396626825, 1504505828677, 5048070509673, 16937798036325, 56831417423689, 190686534309765, 639810795074601

Offset

0,3

Links

Table of n, a(n) for n=0..29.

A. Goupil, M.-E. Pellerin and J. de Wouters d'oplinter, Snake Polyominoes, arXiv preprint arXiv:1307.8432, 2013

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

Mathematica

a[0] = a[1] = 1; a[2] = 3; a[3] = 13; a[4] = 45; a[n_] := a[n] = 3*a[n-1] + 4*a[n-3] + 6; Array[a, 30, 0] (* Jean-François Alcover, Sep 21 2017 *)

Crossrefs

Sequence in context: A115128 A140420 A308087 * A121136 A378069 A350175

Adjacent sequences: A232228 A232229 A232230 * A232232 A232233 A232234

Keyword

nonn

Author

N. J. A. Sloane, Nov 23 2013

Status

approved