OFFSET
0,2
COMMENTS
Equals the central terms of triangle A214398.
LINKS
Robert Israel, Table of n, a(n) for n = 0..336
FORMULA
a(n) = [x^n] 1/(1 - x)^((n+1)^2). - Ilya Gutkovskiy, Oct 04 2017
a(n) ~ n^(n-1/2)*exp(n+5/2)/sqrt(2*Pi). - Robert Israel, Mar 04 2022
MAPLE
seq(binomial(n^2+3*n, n), n=0..30); # Robert Israel, Mar 04 2022
PROG
(PARI) a(n)=binomial(n^2+3*n, n)
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jul 15 2012
STATUS
approved