A189737 a(1)=3, a(2)=3, a(n)=3*a(n-1) + 3*a(n-2).

3, 3, 18, 63, 243, 918, 3483, 13203, 50058, 189783, 719523, 2727918, 10342323, 39210723, 148659138, 563609583, 2136806163, 8101247238, 30714160203, 116446222323, 441481147578, 1673782109703, 6345789771843, 24058715644638, 91213516249443, 345816695682243

Offset

1,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..100

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

Formula

G.f.: 3*x*(1-2*x)/(1-3*x-3*x^2). - Bruno Berselli, May 24 2011

Mathematica

LinearRecurrence[{3, 3}, {3, 3}, 40]

Prog

(Maxima) a[1]:3$ a[2]:3$ a[n]:=3*a[n-1]+3*a[n-2]$ makelist(a[n], n, 1, 26); /* Bruno Berselli, May 24 2011 */

Crossrefs

Cf. A000045, A000079, A105476, A159612, A080040, A135522, A103435, A189732, A189734, A189735, A189736, A189738, A189739, A189741, A189742, A189743, A189744, A189745, A189746, A189747, A189748, A189749.

Sequence in context: A227773 A346380 A371552 * A261567 A096935 A136475

Adjacent sequences: A189734 A189735 A189736 * A189738 A189739 A189740

Keyword

nonn,easy

Author

Harvey P. Dale, Apr 26 2011

Status

approved