A368492 a(n) = Sum_{k=0..n} k^(n+k).

1, 1, 17, 762, 67788, 10034459, 2226678977, 691532161356, 286302140043208, 152380144397396525, 101369101598593980737, 82415052812980817676790, 80402388030057940015721524, 92697243086459794077519471767

Offset: 0

Author

Seiichi Manyama, Dec 27 2023

Keywords

• nonn
• easy

Crossrefs

Cf. A026898, A031971.

Programs

PARI

a(n) = sum(k=0, n, k^(n+k));

Formula

G.f.: Sum_{k>=0} (k^2*x)^k / (1 - k*x).

a(n) ~ n^(2*n). - Vaclav Kotesovec, Dec 27 2023