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 A009569 #17 Jan 22 2018 02:39:16
%S A009569 0,1,-1,5,-20,136,-976,8840,-88640,1019776,-12933376,181318400,
%T A009569 -2767631360,45821372416,-816582578176,15596531778560,
%U A009569 -317710534983680,6876972491309056,-157606194409701376,3812752893951672320,-97090584769337753600,2596013487025352605696
%N A009569 Expansion of e.g.f. sinh(log(1+tan(x))).
%H A009569 G. C. Greubel, <a href="/A009569/b009569.txt">Table of n, a(n) for n = 0..430</a>
%F A009569 a(n) ~ n! * (-1)^(n+1) * 4^n / Pi^(n+1). - _Vaclav Kotesovec_, Jan 23 2015
%t A009569 CoefficientList[Series[(Tan[x]*(2 + Tan[x]))/(2*(1 + Tan[x])), {x, 0, 20}], x] * Range[0, 20]! (* _Vaclav Kotesovec_, Jan 23 2015 *)
%t A009569 With[{nmax = 50}, CoefficientList[Series[Sinh[Log[1 + Tan[x]]], {x, 0, nmax}], x]*Range[0, nmax]!] (* _G. C. Greubel_, Jan 21 2018 *)
%o A009569 (PARI) x='x+O('x^30); concat([0], Vec(serlaplace(sinh(log(1+tan(x)))))) \\ _G. C. Greubel_, Jan 21 2018
%K A009569 sign,easy
%O A009569 0,4
%A A009569 _R. H. Hardin_
%E A009569 Extended with signs by _Olivier Gérard_, Mar 15 1997
%E A009569 Terms a(20) and a(21) added by _G. C. Greubel_, Jan 21 2018