A171557 a(n) = 3^n*A168053(n).

1, 3, -9, -81, -243, -1215, -5103, -15309, -59049, -216513, -649539, -2302911, -7971615, -23914845, -81310473, -272629233, -817887699, -2711943423, -8910671247, -26732013741, -87169610025, -282429536481, -847288609443

Offset

0,2

Comments

Hankel transform of A171556.

Links

Table of n, a(n) for n=0..22.

Index entries for linear recurrences with constant coefficients, signature (3,0,27,-81).

Formula

G.f.: (1-18*x^2-81*x^3)/((1-3*x)^2*(1+3*x+9*x^2)).

Mathematica

CoefficientList[Series[(1 - 18 x^2 - 81 x^3)/((1 - 3 x)^2*(1 + 3 x + 9 x^2)), {x, 0, 30}], x] (* Wesley Ivan Hurt, Jan 21 2017 *)

Prog

(PARI) Vec((1-18*x^2-81*x^3)/((1-3*x)^2*(1+3*x+9*x^2)) + O(x^30)) \\ Michel Marcus, Feb 10 2015

Crossrefs

Cf. A168053, A171556.

Sequence in context: A259986 A124049 A067623 * A055156 A047912 A078684

Adjacent sequences: A171554 A171555 A171556 * A171558 A171559 A171560

Keyword

easy,sign

Author

Paul Barry, Dec 11 2009

Status

approved