OFFSET
0,5
FORMULA
a(n) = [x^n] 1 / (1 - Sum_{d|n, d <= sqrt(n)} x^d).
a(p) = 1, where p is prime.
MATHEMATICA
a[n_] := SeriesCoefficient[1/(1 - Sum[Boole[d <= Sqrt[n]] x^d, {d, Divisors[n]}]), {x, 0, n}]; Table[a[n], {n, 0, 45}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Sep 24 2019
STATUS
approved