OFFSET
0,2
FORMULA
G.f.: Product_{k>=1} ((1 + x^k)/(1 - x^k))^(mu(k)*k).
EXAMPLE
G.f.: A(x) = 1 + 2*x - 2*x^2 - 12*x^3 - 10*x^4 + 12*x^5 + 44*x^6 + 40*x^7 - 26*x^8 - 132*x^9 - 60*x^10 + ...
MATHEMATICA
terms = 44; CoefficientList[Series[Product[((1 + x^k)/(1 - x^k))^(MoebiusMu[k] k), {k, 1, terms}], {x, 0, terms}], x]
terms = 44; A[_] = 1; Do[A[x_] = (1 + x)/((1 - x) Product[A[x^k]^k, {k, 2, terms}]) + O[x]^(terms + 1) // Normal, terms + 1]; CoefficientList[A[x], x]
CROSSREFS
KEYWORD
sign
AUTHOR
Ilya Gutkovskiy, Apr 20 2019
STATUS
approved