OFFSET
0,2
COMMENTS
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (27,-243,729).
FORMULA
From Vincenzo Librandi, Feb 07 2013: (Start)
G.f.: 9*x*(1+9*x)/(1-9*x)^3.
a(n) = 27*a(n-1) - 243*a(n-2) + 729*a(n-3). (End)
E.g.f.: 9*x*(9*x+1)*exp(9*x). - Elmo R. Oliveira, Dec 25 2025
MATHEMATICA
CoefficientList[Series[9 x (1 + 9 x)/(1 - 9 x)^3, {x, 0, 30}], x] (* or *) LinearRecurrence[{27, -243, 729}, {0, 9, 324}, 20] (* Vincenzo Librandi, Feb 07 2013 *)
PROG
(Magma) [n^2*9^n: n in [0..20]]; // Vincenzo Librandi, Feb 07 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Mohammad K. Azarian, Apr 07 2007
STATUS
approved