OFFSET
0,2
FORMULA
G.f.: B(x)^2 where B(x) is the g.f. of A379287.
a(n) = 2 * Sum_{k=0..n} binomial(2*n+5*k+2,k) * binomial(3*n+3*k+1,n-k)/(2*n+5*k+2).
PROG
(PARI) a(n) = 2*sum(k=0, n, binomial(2*n+5*k+2, k)*binomial(3*n+3*k+1, n-k)/(2*n+5*k+2));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Dec 19 2024
STATUS
approved