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Dirichlet g.f.: Product_{k>=2} (1 - k^(-s))^2.
8

%I #5 Dec 14 2020 10:28:26

%S 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,

%T -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,

%U -2,-4,-2,2,4,-2,2,2,-2,4,2,2,-2,-4,-2,2,4,4,2,2,-2,-2

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

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

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

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

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

%K sign

%O 1,2

%A _Ilya Gutkovskiy_, Dec 13 2020