OFFSET
0,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..1000
FORMULA
G.f.: A(x) = 1/(1-x)^2 + x^2*A(x)^3.
a(n) = Sum_{k=0..floor(n/2)} binomial(n+2*k+1,4*k+1) * binomial(3*k,k) / (2*k+1). - Seiichi Manyama, Jul 30 2023
PROG
(PARI) a(n) = sum(k=0, n\2, binomial(n+2*k+1, 4*k+1)*binomial(3*k, k)/(2*k+1)); \\ Seiichi Manyama, Jul 30 2023
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jul 24 2003
STATUS
approved