A252710 Sum_{k=0..n} k^(n-k)*(n+k)^k.

2, 19, 270, 5274, 131250, 3971953, 141615782, 5814096100, 270145723914, 14014491434175, 802959561033630, 50357860270776302, 3431283333644097698, 252413829036827831821, 19937800344936448113750, 1683065517269356710047112, 151213514611062314791034874

Offset

1,1

Links

Table of n, a(n) for n=1..17.

Formula

a(n) ~ 2^n * n^n / (1-exp(-1/2)/2). - Vaclav Kotesovec, Dec 20 2014

Mathematica

Table[Sum[k^(n-k)*(n+k)^k, {k, 0, n}], {n, 1, 20}]

Crossrefs

Cf. A062817, A252708, A252709.

Sequence in context: A239108 A191806 A349721 * A065923 A293946 A365652

Adjacent sequences: A252707 A252708 A252709 * A252711 A252712 A252713

Keyword

nonn,easy

Author

Vaclav Kotesovec, Dec 20 2014

Status

approved