OFFSET
0,2
FORMULA
a(n) = Sum_{k=0..n} binomial(n,k) * binomial(2*n+3*k+1,n)/(2*n+3*k+1).
PROG
(PARI) a(n) = sum(k=0, n, binomial(n, k)*binomial(2*n+3*k+1, n)/(2*n+3*k+1));
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Seiichi Manyama, Jul 13 2023
STATUS
approved