A012137 - OEIS

%I #9 Jan 18 2020 19:50:59

%S 1,1,17,673,54305,7334273,1497501873,430436005665,165573876222529,

%T 82074493484054017,50922938856050558289,38644611846710150572193,

%U 35205379514991276523808353,37909794281251146499011279233

%N arctan(arcsin(arctanh(x))) = x + (1/3!)*x^3 + (17/5!)*x^5 + (673/7!)*x^7 + (54305/9!)*x^9 + ...

%t With[{nn=30},Take[CoefficientList[Series[ArcTan[ArcSin[ArcTanh[x]]],{x,0,nn}],x] Range[0,nn-1]!,{2,-1,2}]] (* _Harvey P. Dale_, Jan 18 2020 *)

%K nonn

%O 0,3

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