OFFSET
0,2
LINKS
Winston de Greef, Table of n, a(n) for n = 0..468
FORMULA
a(n) = [x^n] 1/(1 - 9*x*(1-x)^n)^(1/3).
PROG
(PARI) a(n) = (-1)^n*sum(k=0, n, 9^k*binomial(-1/3, k)*binomial(n*k, n-k));
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Mar 27 2023
STATUS
approved