OFFSET
0,3
FORMULA
a(n) = [x^n] Product_{k>=1} 1/(1 - x^k)^(k^(n-1)).
MATHEMATICA
Table[SeriesCoefficient[Exp[Sum[DivisorSigma[n, k] x^k/k, {k, 1, n}]], {x, 0, n}], {n, 0, 16}]
Table[SeriesCoefficient[Product[1/(1 - x^k)^(k^(n - 1)), {k, 1, n}], {x, 0, n}], {n, 0, 16}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Sep 17 2018
STATUS
approved