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
KEYWORD
nonn,easy
AUTHOR
Mohammad K. Azarian, Apr 07 2007
STATUS
approved
