OFFSET
0,2
FORMULA
a(n) = 2 * Sum_{k=0..n} binomial(3*k+2,k) * binomial(k,n-k)/(3*k+2).
G.f.: A(x) = B(x)^2 where B(x) is the g.f. of A364475.
PROG
(PARI) a(n, r=2, s=1, t=3, u=0) = r*sum(k=0, n, binomial(t*k+u*(n-k)+r, k)*binomial(s*k, n-k)/(t*k+u*(n-k)+r));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Mar 28 2024
STATUS
approved