A339701 Dirichlet g.f.: Product_{k>=2} (1 - k^(-s))^2.

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

Offset: 1

Author

Ilya Gutkovskiy, Dec 13 2020

Keywords

• sign

Crossrefs

Cf. A002107, A114592, A301830, A339702, A339703, A339704, A339705, A339706, A339707.

Formula

a(1) = 1; a(n) = -Sum_{d|n, d < n} A301830(n/d) * a(d).

a(n) = Sum_{d|n} A114592(n/d) * A114592(d).

a(p^k) = A002107(k) for prime p.