A102065 - OEIS

%I #11 Sep 26 2020 12:07:17

%S 3,3,63,9,11,63,63,9,3591,693,2277,189,189,21,7161,77,21,3591,171,99,

%T 625779,47817,68103,1323,297,297,16929,171,531,64449

%N Denominators of e.g.f.: -cot(arctanh(x)), odd powers only.

%e cot(arctanh(x)) = 1/x - (2/3)*x - (4/3)*x^3/3! - (1040/63)*x^5/5! - ...

%t With[{nn=60},Take[CoefficientList[Series[-Cot[ArcTanh[x]],{x,0,nn}],x] Range[ 0,nn-1]!,{2,-1,2}]]//Quiet//Denominator (* _Harvey P. Dale_, Sep 26 2020 *)

%Y Numerators are in A102064.

%K nonn,frac

%O 1,1

%A _Ralf Stephan_, Dec 28 2004