OFFSET
0,2
COMMENTS
Hankel transform of A171556.
LINKS
Index entries for linear recurrences with constant coefficients, signature (3,0,27,-81).
FORMULA
G.f.: (1-18*x^2-81*x^3)/((1-3*x)^2*(1+3*x+9*x^2)).
MATHEMATICA
CoefficientList[Series[(1 - 18 x^2 - 81 x^3)/((1 - 3 x)^2*(1 + 3 x + 9 x^2)), {x, 0, 30}], x] (* Wesley Ivan Hurt, Jan 21 2017 *)
PROG
(PARI) Vec((1-18*x^2-81*x^3)/((1-3*x)^2*(1+3*x+9*x^2)) + O(x^30)) \\ Michel Marcus, Feb 10 2015
CROSSREFS
KEYWORD
easy,sign
AUTHOR
Paul Barry, Dec 11 2009
STATUS
approved