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 A024236 #18 Jun 24 2018 12:28:17
%S A024236 0,1,-2,48,-1040,62720,-4314624,498003968,-70081316864,13529482592256,
%T A024236 -3175495421788160,933402531586899968,-326784893253162369024,
%U A024236 136568449424117316190208,-66517446960602151366164480
%N A024236 Expansion of log(1+tan(x)*x)/2.
%F A024236 E.g.f. of aerated sequence: Sum(n>=0, a(n)*x^(2*n)/(2*n)!) = log(1+tan(x)*x)/2. - _Robert Israel_, Jun 29 2015
%p A024236 S:= series(log(1+tan(x)*x)/2, x, 101): seq(coeff(S, x, 2*j)*(2*j)!, j=0..50); # _Robert Israel_, Jun 29 2015
%t A024236 With[{nn=30},Take[CoefficientList[Series[Log[1+Tan[x]x]/2,{x,0,nn}],x] Range[0,nn]!,{1,-1,2}]] (* _Harvey P. Dale_, Jun 24 2018 *)
%Y A024236 Cf. A009379.
%Y A024236 Cf. A101921.
%K A024236 sign
%O A024236 0,3
%A A024236 _R. H. Hardin_
%E A024236 Extended with signs, Mar 1997
%E A024236 Previous Mathematica program replaced by _Harvey P. Dale_, Jun 24 2018