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

Author

Paul Barry, Dec 11 2009

Keywords

• easy
• sign

Comments

Hankel transform of A171556.

Links

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

Crossrefs

Cf. A168053, A171556.

Programs

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 *)

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

Formula

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