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 A009426 #13 Jun 23 2015 21:43:04
%S A009426 0,1,-1,5,-12,89,-345,3093,-17136,182097,-1334025,16371365,-150969324,
%T A009426 2101489961,-23556117585,367038504693,-4870660226880,84100519126561,
%U A009426 -1293871061371761,24562906630580293,-430689316852061740
%N A009426 Expansion of log(1+x)/cos(sinh(x)).
%F A009426 a(n) ~ (n-1)! * (-1)^(n+1) / cos(sinh(1)). - _Vaclav Kotesovec_, Jan 24 2015
%t A009426 Log[ 1+x ]/Cos[ Sinh[ x ] ]
%t A009426 CoefficientList[Series[Log[1 + x]*Sec[Sinh[x]], {x, 0, 20}], x] * Range[0, 20]! (* _Vaclav Kotesovec_, Jan 24 2015 *)
%K A009426 sign,easy
%O A009426 0,4
%A A009426 _R. H. Hardin_
%E A009426 Extended with signs by _Olivier Gérard_, Mar 15 1997