OFFSET
0,4
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..240
FORMULA
a(n) = [x^n] (Sum_{k=0..n} k^n * x^k)^2.
a(n) ~ sqrt(Pi) * n^(2*n + 1/2) / 2^(2*n + 1). - Vaclav Kotesovec, Dec 07 2021
MATHEMATICA
a[0] = 1; a[n_] := Sum[(k*(n - k))^n, {k, 0, n}]; Array[a, 16, 0] (* Amiram Eldar, Dec 07 2021 *)
PROG
(PARI) a(n) = sum(k=0, n, (k*(n-k))^n);
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Dec 07 2021
STATUS
approved