OFFSET
1,2
FORMULA
a(n) = A036740(n) * Product_{k=1..n} Sum_{j=1..k} (j/k)^n.
a(n) ~ n!^n * c * d^n, where d = exp(-Integral_{x=0..1} log(1 - exp(-1/x)) dx) = 1.187538543919977798892363400109897833660222697152558038684860736484... and c = exp(1 - 1/(exp(1) - 1)) / (exp(1) - 1) = 0.88399704290317414073109479991305699114875723090346..., updated Apr 19 2024
a(n) ~ c * d^n * (2*Pi)^(n/2) * n^(n*(2*n+1)/2) / exp(n^2 - 1/12).
MATHEMATICA
Table[Product[Sum[j^n, {j, 1, k}], {k, 1, n}], {n, 1, 12}]
Table[Product[HarmonicNumber[k, -n], {k, 1, n}], {n, 1, 12}] // FunctionExpand
CROSSREFS
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, Oct 07 2023
STATUS
approved