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 A385470 #15 Jul 04 2025 15:15:04
%S A385470 1,2,8,52,448,4848,62912,952992,16496640,321282816,6952332288,
%T A385470 165489858048,4297340166144,120890184308736,3662409013420032,
%U A385470 118879239686541312,4115985952586858496,151415632063102648320,5897814669785134006272,242489327746828076974080
%N A385470 Expansion of e.g.f. 1/(1 - 2 * arctanh(x)).
%F A385470 E.g.f.: B(x)^2, where B(x) is the e.g.f. of A385468.
%F A385470 E.g.f.: 1/(1 - log((1+x)/(1-x))).
%F A385470 a(n) = Sum_{k=0..n} 2^k * k! * A111594(n,k).
%F A385470 a(n) ~ 2^(3/2) * sqrt(Pi) * (1 + exp(1))^(n-1) * n^(n + 1/2) / (exp(n-1) * (exp(1) - 1)^(n+1)). - _Vaclav Kotesovec_, Jun 30 2025
%t A385470 With[{nn=20},CoefficientList[Series[1/(1-2ArcTanh[x]),{x,0,nn}],x] Range[0,nn]!] (* _Harvey P. Dale_, Jul 04 2025 *)
%o A385470 (PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace(1/(1-2*atanh(x))))
%Y A385470 Cf. A296676, A385471.
%Y A385470 Cf. A111594, A385468.
%K A385470 nonn,easy
%O A385470 0,2
%A A385470 _Seiichi Manyama_, Jun 30 2025