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A129003 (n^3+n^2)*3^n. 1
6, 108, 972, 6480, 36450, 183708, 857304, 3779136, 15943230, 64953900, 257217444, 994857552, 3772168218, 14061928860, 51656065200, 187339329792, 671787127926, 2384960530284, 8391527791740, 29288988968400, 101486346775506 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (12,-54,108,-81).

FORMULA

G.f.: 6x(1+6x)/(1-3x)^4. [From R. J. Mathar, Dec 19 2008]

a(n) = 12*a(n-1)-54*a(n-2)+108*a(n-3)-81*a(n-4). - Vincenzo Librandi, Feb 12 2013

a(n) = 6*(A036216(n-1)+6*A036216(n-2)), with A036216(-1)=0. [Bruno Berselli, Feb 12 2013]

MATHEMATICA

LinearRecurrence[{12, -54, 108, -81}, {6, 108, 972, 6480}, 30] (* Vincenzo Librandi, Feb 12 2013 *)

PROG

(MAGMA) [(n^3+n^2)*3^n: n in [1..25]]; /* or */ I:=[6, 108, 972, 6480]; [n le 4 select I[n] else 12*Self(n-1)-54*Self(n-2)+108*Self(n-3)-81*Self(n-4): n in [1..25]]; // Vincenzo Librandi, Feb 12 2013

CROSSREFS

Cf. A036216, A128796, A036289.

Sequence in context: A006453 A251667 A127213 * A099138 A230540 A295791

Adjacent sequences:  A129000 A129001 A129002 * A129004 A129005 A129006

KEYWORD

nonn,easy

AUTHOR

Mohammad K. Azarian, May 01 2007

STATUS

approved

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Last modified July 13 04:53 EDT 2020. Contains 335673 sequences. (Running on oeis4.)