A012685 - OEIS

%I #6 Aug 20 2024 14:16:50

%S 1,0,12,-480,28560,-2595840,342910656,-62365675008,14932846506240,

%T -4548435497041920,1716639310480919552,-786314410657025941504,

%U 429828791337549223596032,-276479195899367035140833280

%N cosh(tanh(x)*arctan(x))=1+12/4!*x^4-480/6!*x^6+28560/8!*x^8...

%t With[{nn=30},Take[CoefficientList[Series[Cosh[Tanh[x]ArcTan[x]],{x,0,nn}],x] Range[0,nn]!,{1,-1,2}]] (* _Harvey P. Dale_, Aug 20 2024 *)

%K sign

%O 0,3

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