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 A320971 #21 Sep 08 2022 08:46:23
%S A320971 1,-2,-4,2,10,22,-4,-26,-68,-104,-12,110,378,486,448,-66,-1130,-2242,
%T A320971 -3044,-2474,-322,5106,11064,16954,17896,10440,-8032,-40132,-74578,
%U A320971 -105754,-108564,-66534,42672,209858,421352,611946,690204,553534,82112,-735082,-1892200
%N A320971 Expansion of Product_{k>=1} ((1 - x^k)/(1 + x^k))^(sigma(k)).
%H A320971 Seiichi Manyama, <a href="/A320971/b320971.txt">Table of n, a(n) for n = 0..10000</a>
%t A320971 With[{nmax=80}, CoefficientList[Series[Product[((1-q^k)/(1+q^k) )^DivisorSigma[1,k], {k, 1, nmax+2}], {q, 0, nmax}], q]] (* _G. C. Greubel_, Oct 29 2018 *)
%o A320971 (PARI) N=99; x='x+O('x^N); Vec(prod(k=1, N, ((1-x^k)/(1+x^k))^sigma(k)))
%o A320971 (Magma) m:=80; R<q>:=PowerSeriesRing(Rationals(), m); Coefficients(R!( (&*[((1-q^k)/(1+q^k))^DivisorSigma(1,k): k in [1..(m+2)]]) )); // _G. C. Greubel_, Oct 29 2018
%Y A320971 Convolution inverse of A301555.
%Y A320971 Product_{k>=1} ((1 - x^k)/(1 + x^k))^(sigma_b(k)): A320908 (b=0), this sequence (b=1), A320972 (b=2).
%Y A320971 Cf. A000203, A288385, A288421.
%K A320971 sign
%O A320971 0,2
%A A320971 _Seiichi Manyama_, Oct 25 2018