OFFSET
1,2
FORMULA
a(n) = Sum_{k=0..n-1} binomial(n-1,k)^2 * binomial(n,k)^3.
PROG
(PARI) a(n) = sum(k=0, n-1, binomial(n-1, k)^2*binomial(n, k)^3);
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jul 14 2024
STATUS
approved