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 A003700 M5080 #16 Feb 16 2015 08:10:52
%S A003700 1,-1,-19,475,1753,-1109769,70784325,2711086547,-1376283649103,
%T A003700 148592152807663,21812320857733789,-12754009647903010101,
%U A003700 1675171082535404962441,847081835857552788679655
%N A003700 Expansion of tan(x /cosh(x)).
%D A003700 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%t A003700 Tan[ x/Cosh[ x ] ] (* Odd Part *)
%t A003700 nn = 20; Table[(CoefficientList[Series[Tan[x*Sech[x]], {x, 0, 2*nn+1}], x] * Range[0, 2*nn+1]!)[[n]], {n, 2, 2*nn, 2}] (* _Vaclav Kotesovec_, Feb 16 2015 *)
%K A003700 sign
%O A003700 0,3
%A A003700 _R. H. Hardin_, _N. J. A. Sloane_, _Simon Plouffe_