A013448 - OEIS

%I #6 Feb 04 2016 14:52:55

%S 1,0,0,-160,1792,-484224,54495232,-9441003520,2598020579328,

%T -756380393635840,305071008569196544,-144297159065656885248,

%U 81729693136918543335424,-55094722790449057575731200

%N sech(tan(x)-arctan(x))=1-160/6!*x^6+1792/8!*x^8-484224/10!*x^10...

%t With[{nn=30},Take[CoefficientList[Series[Sech[Tan[x]-ArcTan[x]],{x,0,nn}],x] Range[0,nn]!,{1,-1,2}]] (* _Harvey P. Dale_, Feb 04 2016 *)

%K sign

%O 0,4

%A Patrick Demichel (patrick.demichel(AT)hp.com)