%I #9 Aug 10 2019 10:57:38
%S 0,-1,-2,14,568,2144,-1061312,-65851696,3745115008,1232648783744,
%T 50799435228928,-36670923310299136,-8828746813705828352,
%U 954888000296009790464,1122466427244127979911168
%N arctan(log(cos(x)))=-1/2!*x^2-2/4!*x^4+14/6!*x^6+568/8!*x^8...
%t With[{nn=30},Take[CoefficientList[Series[ArcTan[Log[Cos[x]]],{x,0,nn}],x] Range[0,nn]!,{1,-1,2}]] (* _Harvey P. Dale_, Aug 10 2019 *)
%K sign
%O 0,3
%A Patrick Demichel (patrick.demichel(AT)hp.com)
%E Added missing 0 at start, otherwise this is OK. - _N. J. A. Sloane_, Dec 17 2011