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 A299021 #9 Jun 19 2018 22:12:51
%S A299021 1,2,6,22,86,358,1558,6966,31894,148918,705062,3380054,16381158,
%T A299021 80056550,394266950,1955139942,9749771926,48873487942,246160229782,
%U A299021 1244801094742,6318514387638,32184084454166,164425969781062,842429440124854,4327629345403078,22283328480744070
%N A299021 G.f.: A(x) = Sum_{n>=1} a(n)*x^n = x*Product_{n>=1} (1 + a(n)*x^n)/(1 - a(n)*x^n).
%F A299021 G.f.: A(x) = Sum_{n>=1} a(n)*x^n = x*exp(Sum_{k>=1} Sum_{n>=1} (1 + (-1)^(k+1))*a(n)^k*x^(n*k)/k).
%e A299021 G.f.: A(x) = x + 2*x^2 + 6*x^3 + 22*x^4 + 86*x^5 + ... = x * ((1 + x) * (1 + 2*x^2) * (1 + 6*x^3) * (1 + 22*x^4) * (1 + 86*x^5) * ...) / ((1 - x) * (1 - 2*x^2) * (1 - 6*x^3) * (1 - 22*x^4) * (1 - 86*x^5) * ...).
%t A299021 a[n_] := a[n] = SeriesCoefficient[x Product[(1 + a[k] x^k)/(1 - a[k] x^k), {k, 1, n - 1}], {x, 0, n}]; a[1] = 1; Table[a[n], {n, 26}]
%t A299021 a[n_] := a[n] = SeriesCoefficient[x Exp[Sum[Sum[(1 + (-1)^(k + 1)) a[j]^k x^(j k)/k, {j, 1, n - 1}], {k, 1, n - 1}]], {x, 0, n}]; a[1] = 1; Table[a[n], {n, 26}]
%Y A299021 Cf. A032305, A073075, A093637.
%K A299021 nonn
%O A299021 1,2
%A A299021 _Ilya Gutkovskiy_, Jun 18 2018