

A128969


a(n) = (n^3  n)*9^n.


1



0, 486, 17496, 393660, 7085880, 111602610, 1607077584, 21695547384, 278942752080, 3451916556990, 41422998683880, 484649084601396, 5551434969070536, 62453643402043530, 691794203838020640
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OFFSET

1,2


LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (36,486,2916,6561).


FORMULA

G.f.: 486x^2/(19x)^4. a(n)=486*A038291(n+1,3).  R. J. Mathar, Dec 19 2008
a(n) = 36*a(n1) 486*a(n2) +2916*a(n3) 6561*a(n4).  Vincenzo Librandi, Feb 11 2013


MATHEMATICA

CoefficientList[Series[486 x/(1  9 x)^4, {x, 0, 30}], x] (* Vincenzo Librandi, Feb 11 2013 *)


PROG

(MAGMA) [(n^3n)*9^n: n in [0..25]]; (* or *) I:=[0, 486, 17496, 393660]; [n le 4 select I[n] else 36*Self(n1)  486*Self(n2) + 2916*Self(n3)  6561*Self(n4): n in [1..25]]; // Vincenzo Librandi, Feb 11 2013


CROSSREFS

Cf. A128796, A036289.
Sequence in context: A187860 A205240 A206146 * A223412 A097765 A179428
Adjacent sequences: A128966 A128967 A128968 * A128970 A128971 A128972


KEYWORD

nonn,easy


AUTHOR

Mohammad K. Azarian, Apr 28 2007


EXTENSIONS

Offset corrected by Mohammad K. Azarian, Nov 20 2008


STATUS

approved



