OFFSET
0,3
FORMULA
a(n) ~ 2^(n*(n + 3/2)) * n^(n*(n+1)) / (3^n * exp(n^2 - 11/24)). - Vaclav Kotesovec, Sep 25 2020
MATHEMATICA
Table[((2*n + 1)!!)^n * Sum[1/(2*k + 1)^n, {k, 1, n}], {n, 0, 10}] (* Vaclav Kotesovec, Sep 25 2020 *)
PROG
(PARI) {a(n) = prod(k=1, n, 2*k+1)^n*sum(k=1, n, 1/(2*k+1)^n)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Sep 12 2020
STATUS
approved