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 A319457 #4 Sep 19 2018 19:30:38
%S A319457 1,1,7,31,175,931,5209,29114,165087,940828,5396777,31090962,179832625,
%T A319457 1043516371,6072302726,35420582431,207051636799,1212583329959,
%U A319457 7113193757656,41788933655049,245831162935825,1447891754747672,8537111315442222,50387162650271055,297664212003582753
%N A319457 a(n) = [x^n] Product_{k>=1} 1/((1 - x^k)*(1 - x^(2*k)))^n.
%F A319457 a(n) = [x^n] Product_{k>=1} (1 + x^k)^n/(1 - x^(2*k))^(2*n).
%F A319457 a(n) = [x^n] exp(n*Sum_{k>=1} (4*sigma(k) - sigma(2*k))*x^k/k).
%t A319457 Table[SeriesCoefficient[Product[1/((1 - x^k) (1 - x^(2 k)))^n , {k, 1, n}], {x, 0, n}], {n, 0, 24}]
%t A319457 Table[SeriesCoefficient[1/(QPochhammer[x] QPochhammer[x^2])^n, {x, 0, n}], {n, 0, 24}]
%t A319457 Table[SeriesCoefficient[Exp[n Sum[(4 DivisorSigma[1, k] - DivisorSigma[1, 2 k]) x^k/k, {k, 1, n}]], {x, 0, n}], {n, 0, 24}]
%Y A319457 Cf. A002513, A008485, A270919, A296043, A296044, A319455, A319456.
%K A319457 nonn
%O A319457 0,3
%A A319457 _Ilya Gutkovskiy_, Sep 19 2018