A013354 - OEIS

%I #6 Jul 05 2019 15:54:21

%S -3,-15,-273,7185,893607,110604585,6777315087,-405484606815,

%T -441813428161833,-137423041821531015,-28797568231809153153,

%U 2268330081740331047985,6518378202627257740085127

%N arctan(sin(x)-tan(x))=-3/3!*x^3-15/5!*x^5-273/7!*x^7+7185/9!*x^9...

%t With[{nn=30},Take[CoefficientList[Series[ArcTan[Sin[x]-Tan[x]],{x,0,nn}],x] Range[0,nn-1]!,{4,-1,2}]] (* _Harvey P. Dale_, Jul 05 2019 *)

%K sign

%O 0,1

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