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 A296628 #11 Jan 31 2022 21:13:23
%S A296628 1,4,16,1408,13568,606208,61878272,1956380672,21143027712,
%T A296628 348742016303104,279852224852525056,5217315235815227392,
%U A296628 118411884225053589504,842233813811702133686272,4096134057254358725165056,3447514330976633343761929207808,44711197753944482628093599547392
%N A296628 Numerators of coefficients in expansion of e.g.f. tan(x)/tanh(x) (even powers only).
%C A296628 The values of the denominators are similar to A006656 up to n = 138, but differ after.
%H A296628 G. C. Greubel, <a href="/A296628/b296628.txt">Table of n, a(n) for n = 0..150</a>
%F A296628 Numerators of coefficients in expansion of e.g.f. tanh(x)/tan(x) (even powers only, absolute values).
%F A296628 Numerators of coefficients in expansion of e.g.f. sin(x)*cosh(x)/(sinh(x)*cos(x)) (even powers only).
%e A296628 tan(x)/tanh(x) = 1 + (4/3)*x^2/2! + (16/3)*x^4/4! + (1408/21)*x^6/6! + (13568/9)*x^8/8! + ...
%t A296628 nmax = 16; Numerator[Table[(CoefficientList[Series[Tan[x]/Tanh[x], {x, 0, 2 nmax}], x] Range[0, 2 nmax]!)[[n]], {n, 1, 2 nmax + 1, 2}]]
%o A296628 (Magma)
%o A296628 m:=50; R<x>:=PowerSeriesRing(Rationals(), m);
%o A296628 b:= Coefficients(R!(Laplace( Tan(x)/Tanh(x) )));
%o A296628 [Numerator( b[2*n-1] ): n in [1..Floor((m-2)/2)]]; // _G. C. Greubel_, Jan 31 2022
%o A296628 (Sage) [numerator( factorial(2*n)*( tan(x)/tanh(x) ).series(x, 2*n+3).list()[2*n] ) for n in (0..40)] # _G. C. Greubel_, Jan 31 2022
%Y A296628 Cf. A000182, A000795, A000965, A006656, A024342.
%K A296628 nonn,frac
%O A296628 0,2
%A A296628 _Ilya Gutkovskiy_, Dec 17 2017