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 A013236 #11 Aug 02 2018 02:36:24
%S A013236 0,0,-1,0,-6,8,-150,448,-7560,38432,-642600,4827328,-83392848,
%T A013236 846371264,-15413462064,198308799232,-3850826179200,59939510237696,
%U A013236 -1248952432920192,22723443584373760,-509532711855338240,10564033699974222848,-255033199091475264768
%N A013236 Expansion of e.g.f. tan(log(x+1) - tan(x)).
%H A013236 Vincenzo Librandi, <a href="/A013236/b013236.txt">Table of n, a(n) for n = 0..200</a>
%e A013236 -1/2!*x^2 - 6/4!*x^4 + 8/5!*x^5 - 150/6!*x^6 ...
%t A013236 Range[0, 25]! CoefficientList[Series[Tan[Log[x + 1] - Tan[x]], {x, 0, 25}], x] (* _Vincenzo Librandi_, Aug 02 2018 *)
%o A013236 (PARI) x = 'x + O('x^30); concat([0, 0], Vec(serlaplace(tan(log(x+1) - tan(x))))) \\ _Michel Marcus_, Aug 02 2018
%K A013236 sign
%O A013236 0,5
%A A013236 Patrick Demichel (patrick.demichel(AT)hp.com)
%E A013236 a(0)=a(1)=0 inserted and title improved by _Sean A. Irvine_, Aug 01 2018