%I #6 Nov 28 2016 18:53:27
%S 0,2,-16,128,9984,-1686528,211630080,-21438504960,-115777536000,
%T 1290343156285440,-677718502185369600,262776565415742013440,
%U -69499554745499013611520,-9137401716948937432104960
%N tanh(arctan(x)*arctan(x))=2/2!*x^2-16/4!*x^4+128/6!*x^6+9984/8!*x^8...
%t With[{nn=30},Take[CoefficientList[Series[Tanh[ArcTan[x]*ArcTan[x]],{x,0,nn}],x] Range[0,nn]!,{1,-1,2}]] (* _Ray Chandler_, Nov 28 2016 *)
%K sign
%O 0,2
%A Patrick Demichel (patrick.demichel(AT)hp.com)
|