A128795 n^3*9^n.

0, 9, 648, 19683, 419904, 7381125, 114791256, 1640558367, 22039921152, 282429536481, 3486784401000, 41768190339579, 488038239039168, 5584479224838813, 62773918496412984, 694882570819440375

Offset

0,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (36,-486,2916,-6561).

Formula

G.f.: 9*x*(1+36*x+81*x^2)/(1-9*x)^4. [R. J. Mathar, Dec 19 2008]

a(n) = 36*a(n-1) -486*a(n-2) +2916*a(n-3) -6561*a(n-4). - Vincenzo Librandi, Feb 10 2013

Mathematica

CoefficientList[Series[9 x (1 + 36 x + 81 x^2)/(1 - 9 x)^4, {x, 0, 30}], x] (* Vincenzo Librandi, Feb 10 2013 *)

Prog

(Magma) [n^3*9^n: n in [0..20]]; // Vincenzo Librandi, Feb 10 2013

Crossrefs

Cf. A036289, A007758.

Sequence in context: A211611 A280904 A210053 * A323425 A191510 A081232

Adjacent sequences: A128792 A128793 A128794 * A128796 A128797 A128798

Keyword

nonn,easy

Author

Mohammad K. Azarian, Apr 07 2007

Status

approved