OFFSET
0,3
FORMULA
a(n) = [x^n] Product_{d|n} 1 / (1 - mu(n/d)^2 * x^d).
MATHEMATICA
a[n_] := SeriesCoefficient[Product[1/(1 - MoebiusMu[n/d]^2 x^d), {d, Divisors[n]}], {x, 0, n}]; Table[a[n], {n, 0, 75}]
PROG
(Magma) [1] cat [#RestrictedPartitions(n, {d:d in Divisors(n)|IsSquarefree(n div d)}):n in [1..75]]; // Marius A. Burtea, Sep 20 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Sep 20 2019
STATUS
approved