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 A326238 #30 Jan 07 2023 04:03:00
%S A326238 1,-2,12,-20,30,-24,56,-104,117,-60,132,-240,182,-112,360,-464,306,
%T A326238 -234,380,-600,672,-264,552,-1248,775,-364,1080,-1120,870,-720,992,
%U A326238 -1952,1584,-612,1680,-2340,1406,-760,2184,-3120,1722,-1344,1892,-2640,3510,-1104,2256
%N A326238 Expansion of Sum_{k>=1} k * x^k * (1 - x^k) / (1 + x^k)^3.
%H A326238 Amiram Eldar, <a href="/A326238/b326238.txt">Table of n, a(n) for n = 1..10000</a>
%F A326238 G.f.: Sum_{k>=1} (-1)^(k + 1) * k^2 * x^k / (1 - x^k)^2.
%F A326238 a(n) = n * Sum_{d|n} (-1)^(d + 1) * d.
%F A326238 a(n) = n * A002129(n).
%F A326238 Multiplicative with a(2^e) = 2^e*(3-2^(e+1)), and a(p^e) = p^e*(p^(e+1)-1)/(p-1) if p > 2. - _Amiram Eldar_, Dec 05 2022
%F A326238 Dirichlet g.f.: zeta(s-1)*zeta(s-2)*(1-2^(3-s)). - _Amiram Eldar_, Jan 07 2023
%t A326238 nmax = 47; CoefficientList[Series[Sum[k x^k (1 - x^k)/(1 + x^k)^3, {k, 1, nmax}], {x, 0, nmax}], x] // Rest
%t A326238 Table[n Sum[(-1)^(d + 1) d, {d, Divisors[n]}], {n, 1, 47}]
%t A326238 f[p_, e_] := p^e*(p^(e+1)-1)/(p-1); f[2, e_] := 2^e*(3-2^(e+1)); a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* _Amiram Eldar_, Dec 05 2022 *)
%o A326238 (PARI) a(n)={n*sumdiv(n, d, (-1)^(d + 1) * d)} \\ _Andrew Howroyd_, Sep 10 2019
%Y A326238 Cf. A002129, A064987, A113184, A143520, A185152, A326125.
%K A326238 sign,mult
%O A326238 1,2
%A A326238 _Ilya Gutkovskiy_, Sep 10 2019