%I #11 Aug 15 2014 03:18:10
%S 1,1,1,-3,-15,49,609,-1859,-48031,119617,6247681,-10283171,
%T -1214813487,678311217,330587407201,246695568861,-120086685689663,
%U -270153706006015,56186566871496961,221300400903581245
%N E.g.f.: exp(arctan(arctan(x))) = 1+x+1/2!*x^2-3/3!*x^3-15/4!*x^4+49/5!*x^5...
%H Vincenzo Librandi, <a href="/A012203/b012203.txt">Table of n, a(n) for n = 0..200</a>
%t With[{nn=20},CoefficientList[Series[Exp[ArcTan[ArcTan[x]]],{x,0,nn}],x] Range[0,nn]!] (* _Harvey P. Dale_, Aug 14 2014 *)
%K sign
%O 0,4
%A Patrick Demichel (patrick.demichel(AT)hp.com)
%E Definition edited and clarified by _Harvey P. Dale_, Aug 14 2014