This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A339717 #5 Dec 14 2020 16:00:46
%S A339717 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,
%T A339717 -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,
%U A339717 -2,0,-2,2,0,5,2,2,-2,0,2,2,-2,-4,-2,2,0,0,2,2,-2,-4
%N A339717 Dirichlet g.f.: Product_{k>=2} 1 / (1 + k^(-s))^2.
%F A339717 a(1) = 1; a(n) = -Sum_{d|n, d < n} A328706(n/d) * a(d).
%F A339717 a(n) = Sum_{d|n} A316441(n/d) * A316441(d).
%F A339717 a(p^k) = A022597(k) for prime p.
%Y A339717 Cf. A022597, A316441, A328706, A339718, A339719, A339720, A339721, A339722.
%K A339717 sign
%O A339717 1,2
%A A339717 _Ilya Gutkovskiy_, Dec 14 2020