A012083 - OEIS

%I #8 Feb 05 2015 11:49:32

%S 1,5,129,8133,949281,177127653,48290752353,18102997908453,

%T 8931245615625921,5609823664317348165,4370983985597526359745,

%U 4137308650120582099800453,4676183786000402886175691745

%N arctanh(arcsin(tan(x)))=x+5/3!*x^3+129/5!*x^5+8133/7!*x^7+949281/9!*x^9...

%F a(n) ~ (2*n)! / (arctan(sin(1)))^(2*n+1). - _Vaclav Kotesovec_, Feb 05 2015

%t With[{nn=30},Take[CoefficientList[Series[ArcTanh[ArcSin[Tan[x]]],{x,0,nn}],x] Range[0,nn-1]!,{2,-1,2}]] (* _Harvey P. Dale_, Nov 26 2014 *)

%K nonn

%O 0,2

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