A291676 Main diagonal of A291656.

0, 1, 10, 3527, 123296356, 757031629267449, 1263498691933197473321646, 823340843273442113630752833831086703, 285062591046216676379736060856308430344065653125000

Offset: 0

Author

Seiichi Manyama, Aug 29 2017

Keywords

• nonn

Links

• Seiichi Manyama, Table of n, a(n) for n = 0..27

Crossrefs

Cf. A291656, A335096.

Programs

Mathematica

Table[((2*n - 1)!!)^n * Sum[1/(2*k - 1)^n, {k, 1, n}], {n, 0, 10}] (* Vaclav Kotesovec, Sep 25 2020 *)

Formula

a(n) = ((2n-1)!!)^n * Sum_{i=1..n} 1/(2*i-1)^n.

a(n) ~ 2^(n*(2*n + 1)/2) * n^(n^2) / exp(n^2 + 1/24). - Vaclav Kotesovec, Sep 25 2020