OFFSET
0,2
FORMULA
a(n) ~ c * n^(n*(n+1)/2 + 1/12 + exp(-1)/2) / exp(n^2/4 - n*exp(-1)), where c = 1.981849007720509372587479129359338230641860983165241915197508762536...
MATHEMATICA
Table[Product[1 + Sum[Binomial[m, k]*k^k, {k, 1, m}], {m, 0, n}], {n, 0, 12}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, Oct 29 2017
STATUS
approved