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 A302543 #4 Apr 09 2018 22:34:02
%S A302543 1,5,69,2001,104073,8723549,1088372557,190057979177,44285819490065,
%T A302543 13267464006201781,4964113699657822805,2266816666007859759489,
%U A302543 1239999748307938170531225,800189083150907165762837517,601369618369661775955962338653,520607107122686183781743903500505
%N A302543 Expansion of e.g.f. arctanh(x)/cos(x) (odd powers only).
%F A302543 a(n) = (2*n+1)! * [x^(2*n+1)] arctanh(x)/cos(x).
%e A302543 arctanh(x)/cos(x) = x/1! + 5*x^3/3! + 69*x^5/5! + 2001*x^7/7! + 104073*x^9/9! + ...
%t A302543 nmax = 16; Table[(CoefficientList[Series[ArcTanh[x]/Cos[x], {x, 0, 2 nmax + 1}], x] Range[0, 2 nmax + 1]!)[[n]], {n, 2, 2 nmax, 2}]
%Y A302543 Cf. A000182, A000364, A000795, A002084, A003701, A003702, A010050, A012840, A296743, A301942, A302444, A302542.
%K A302543 nonn
%O A302543 0,2
%A A302543 _Ilya Gutkovskiy_, Apr 09 2018