A339717 Dirichlet g.f.: Product_{k>=2} 1 / (1 + k^(-s))^2.

1, -2, -2, 1, -2, 2, -2, -2, 1, 2, -2, 0, -2, 2, 2, 4, -2, 0, -2, 0, 2, 2, -2, 4, 1, 2, -2, 0, -2, 2, -2, -4, 2, 2, 2, 2, -2, 2, 2, 4, -2, 2, -2, 0, 0, 2, -2, -4, 1, 0, 2, 0, -2, 4, 2, 4, 2, 2, -2, 0, -2, 2, 0, 5, 2, 2, -2, 0, 2, 2, -2, -4, -2, 2, 0, 0, 2, 2, -2, -4

Offset: 1

Author

Ilya Gutkovskiy, Dec 14 2020

Keywords

• sign

Crossrefs

Cf. A022597, A316441, A328706, A339718, A339719, A339720, A339721, A339722.

Formula

a(1) = 1; a(n) = -Sum_{d|n, d < n} A328706(n/d) * a(d).

a(n) = Sum_{d|n} A316441(n/d) * A316441(d).

a(p^k) = A022597(k) for prime p.