OFFSET
0,2
REFERENCES
L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 199, #3.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (12,-27).
FORMULA
a(n) = 9^n - 3^n; a(n) = 12*a(n-1) - 27*a(n-2) for n > 1. - Vincenzo Librandi, Jun 03 2011
G.f.: 6*x/((1-3*x)*(1-9*x)). - Vincenzo Librandi, Oct 04 2014
a(n) = 6*A016142(n). - R. J. Mathar, Nov 23 2018
MAPLE
MATHEMATICA
Table[9^n - 3^n, {n, 0, 25}] (* or *) CoefficientList[Series[6 x /((1 - 3 x) (1 - 9 x)), {x, 0, 30}], x] (* Vincenzo Librandi, Oct 04 2014 *)
PROG
(Magma) [9^n-3^n: n in [0..20]]; // Vincenzo Librandi, Jun 03 2011
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Jan 30 2001
STATUS
approved