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 A364343 #32 Jul 20 2023 10:47:02
%S A364343 1,-1,9,-12,20,-12,35,-60,72,-30,77,-132,104,-56,210,-256,170,-117,
%T A364343 209,-320,378,-132,299,-672,425,-182,594,-588,464,-360,527,-1040,858,
%U A364343 -306,910,-1224,740,-380,1170,-1640,902,-672,989,-1364,1890,-552,1175,-2928,1470,-775,1938,-1872,1484,-1080,2090
%N A364343 Expansion of Sum_{k>0} k * x^k/(1 + x^k)^3.
%H A364343 Seiichi Manyama, <a href="/A364343/b364343.txt">Table of n, a(n) for n = 1..10000</a>
%F A364343 a(n) = (n/2) * Sum_{d|n} (-1)^(d+1) * (d+1) = (n/2) * (A002129(n) + A048272(n)).
%t A364343 a[n_] := DivisorSum[n, (-1)^(# + 1)*(# + 1) &] * n/2; Array[a, 55] (* _Amiram Eldar_, Jul 20 2023 *)
%o A364343 (PARI) my(N=60, x='x+O('x^N)); Vec(sum(k=1, N, k*x^k/(1+x^k)^3))
%Y A364343 Cf. A320900, A364351.
%Y A364343 Cf. A002129, A048272, A309731.
%K A364343 sign
%O A364343 1,3
%A A364343 _Seiichi Manyama_, Jul 19 2023