OFFSET
0,3
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (9,-27,27).
FORMULA
G.f.: 18*x^2/(1-3*x)^3. - Vincenzo Librandi, Feb 10 2013
a(n) = 18*A027472(n+1). - R. J. Mathar, Apr 26 2015
MATHEMATICA
CoefficientList[Series[18 x^2/(1 - 3 x)^3, {x, 0, 30}], x] (* Vincenzo Librandi, Feb 10 2013 *)
LinearRecurrence[{9, -27, 27}, {0, 0, 18}, 40] (* Harvey P. Dale, Dec 15 2014 *)
PROG
(Magma) [(n^2-n)*3^n: n in [0..25]]; // Vincenzo Librandi, Feb 10 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Mohammad K. Azarian, Apr 07 2007
STATUS
approved