Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.
%I #6 Nov 06 2020 16:12:18
%S 1,1,-11,349,-22007,2312601,-365164227,80916522933,-23968582079343,
%T 9151870592718513,-4378918837383018747,2566828786036427906445,
%U -1809533477302236292739175,1510703360292377534570508105
%N cosh(arctan(arcsinh(x)))=1+1/2!*x^2-11/4!*x^4+349/6!*x^6-22007/8!*x^8...
%t With[{nn=30},Take[CoefficientList[Series[Cosh[ArcTan[ArcSinh[x]]],{x,0,nn}],x] Range[0,nn]!,{1,-1,2}]] (* _Harvey P. Dale_, Nov 06 2020 *)
%K sign
%O 0,3
%A Patrick Demichel (patrick.demichel(AT)hp.com)