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 A047691 #9 Mar 07 2020 01:53:40
%S A047691 1,1,1,1,3,37,59,137,871,41641,325249,3887,35797,241586893,24362249,
%T A047691 5721418891,342232522657,4315903789009,8224154352439,2832484672207,
%U A047691 23157229065769,183184249105857781,9926476934520521,2154299222076719401
%N A047691 Numerators of coefficients in Taylor series for exp(tan(x)).
%D A047691 CRC Standard Mathematical Tables and Formulae, 30th ed. 1996, p. 42.
%e A047691 1 + 1*x + (1/2)*x^2 + (1/2)*x^3 + (3/8)*x^4 + (37/120)*x^5 + (59/240)*x^6 + (137/720)*x^7 + (871/5760)*x^8 + ...
%t A047691 Numerator[CoefficientList[Series[Exp[Tan[x]],{x,0,30}],x]] (* _Harvey P. Dale_, May 19 2015 *)
%Y A047691 Cf. A047692, A006229.
%K A047691 nonn,easy,frac
%O A047691 0,5
%A A047691 _N. J. A. Sloane_