OFFSET
1,4
FORMULA
G.f. A(x) satisfies: A(x) = x - Sum_{k>=2} A001065(k) * A(x^k).
Dirichlet g.f.: 1 / (1 + zeta(s-1) * (zeta(s) - 1)).
MATHEMATICA
a[n_] := If[n == 1, n, -Sum[If[d > 1, (DivisorSigma[1, d] - d) a[n/d], 0], {d, Divisors[n]}]]; Table[a[n], {n, 65}]
PROG
(PARI) lista(nn) = {my(va=vector(nn)); va[1] = 1; for (n=2, nn, va[n] = -sumdiv(n, d, if (d>1, (sigma(d) - d) * va[n/d])); ); va; } \\ Michel Marcus, May 15 2020
CROSSREFS
KEYWORD
sign
AUTHOR
Ilya Gutkovskiy, May 14 2020
STATUS
approved