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 A013301 #11 Nov 29 2016 10:48:06
%S A013301 0,1,6,150,7560,650160,84823200,15617281680,3855823171200,
%T A013301 1229340262550400,491641405006752000,241000527467642342400,
%U A013301 142107676844443620710400,99236357585615999548800000
%N A013301 E.g.f.: arctanh(arctanh(x)-log(x+1)).
%F A013301 a(n) ~ (2*n-1)! / (1-exp(-2))^n. - _Vaclav Kotesovec_, Feb 05 2015
%e A013301 1/2!*x^2 + 6/4!*x^4 + 150/6!*x^6 + 7560/8!*x^8 + ...
%t A013301 nn = 20; Table[(CoefficientList[Series[ArcTanh[ArcTanh[x] - Log[1 + x]], {x, 0, 2*nn}], x] * Range[0, 2*nn]!)[[n]], {n, 1, 2*nn+1, 2}] (* _Vaclav Kotesovec_, Feb 05 2015 *)
%Y A013301 Cf. A219863.
%K A013301 nonn
%O A013301 0,3
%A A013301 Patrick Demichel (patrick.demichel(AT)hp.com)
%E A013301 Definition clarified by _Vaclav Kotesovec_, Feb 05 2015
%E A013301 Prepended missing a(0)=0 from _Vaclav Kotesovec_, Feb 05 2015