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A339717
Dirichlet g.f.: Product_{k>=2} 1 / (1 + k^(-s))^2.
8
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
1,2
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.
KEYWORD
sign
AUTHOR
Ilya Gutkovskiy, Dec 14 2020
STATUS
approved