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 A339719 #5 Dec 14 2020 16:00:57
%S A339719 1,-4,-4,6,-4,12,-4,-8,6,12,-4,-12,-4,12,12,17,-4,-12,-4,-12,12,12,-4,
%T A339719 20,6,12,-8,-12,-4,-20,-4,-28,12,12,12,10,-4,12,12,20,-4,-20,-4,-12,
%U A339719 -12,12,-4,-48,6,-12,12,-12,-4,20,12,20,12,12,-4,4,-4,12,-12,38,12,-20,-4,-12,12,-20
%N A339719 Dirichlet g.f.: Product_{k>=2} 1 / (1 + k^(-s))^4.
%F A339719 a(1) = 1; a(n) = -Sum_{d|n, d < n} A339336(n/d) * a(d).
%F A339719 a(p^k) = A022599(k) for prime p.
%Y A339719 Cf. A022599, A316441, A339336, A339717, A339718, A339720, A339721, A339722.
%K A339719 sign
%O A339719 1,2
%A A339719 _Ilya Gutkovskiy_, Dec 14 2020