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 A009371 #14 Jun 22 2015 22:22:44
%S A009371 0,1,1,4,0,45,-155,1748,-13496,151169,-1682191,22018412,-307464872,
%T A009371 4746159613,-78744546907,1410956472396,-27026759291728,
%U A009371 552443153007777,-11988735452427903,275451486233018100,-6677966707663119664
%N A009371 Expansion of log(1+tan(x))*exp(x).
%F A009371 a(n) ~ (n-1)! * (-1)^(n+1) * exp(-Pi/4) * (4/Pi)^n. - _Vaclav Kotesovec_, Jan 23 2015
%t A009371 Log[ 1+Tan[ x ] ]*Exp[ x ]
%t A009371 CoefficientList[Series[E^x*Log[1 + Tan[x]], {x, 0, 20}], x] * Range[0, 20]! (* _Vaclav Kotesovec_, Jan 23 2015 *)
%K A009371 sign,easy
%O A009371 0,4
%A A009371 _R. H. Hardin_
%E A009371 Extended with signs by _Olivier Gérard_, Mar 15 1997