OFFSET
0,2
FORMULA
a(n) ~ 3 * n^n.
MATHEMATICA
nmax = 20; CoefficientList[Series[(1 + Sum[n^n * x^n, {n, 1, nmax}])^3, {x, 0, nmax}], x]
CROSSREFS
KEYWORD
nonn
AUTHOR
Vaclav Kotesovec, Dec 03 2021
STATUS
approved