OFFSET
1,4
FORMULA
G.f. A(x) satisfies: A(x) = x - (x/(1 - x)) * Sum_{k>=1} (1 - x^k) * A(x^k).
MATHEMATICA
a[1] = 1; a[n_] := a[n] = -Sum[a[Floor[(n - 1)/k]], {k, 1, n - 1}]; Table[a[n], {n, 1, 65}]
nmax = 65; A[_] = 0; Do[A[x_] = x - (x/(1 - x)) Sum[(1 - x^k) A[x^k], {k, 1, nmax}] + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x] // Rest
CROSSREFS
KEYWORD
sign
AUTHOR
Ilya Gutkovskiy, Aug 11 2021
STATUS
approved