OFFSET
0,2
FORMULA
a(n) = 4 if n is a prime (A000040).
MATHEMATICA
Table[SeriesCoefficient[Product[(1 + Boole[Mod[n, k] == 0] x^k)/(1 - Boole[Mod[n, k] == 0] x^k), {k, 1, n}], {x, 0, n}], {n, 0, 65}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Mar 08 2018
STATUS
approved