cosh(arctan(tanh(x)))=1+1/2!*x^2-15/4!*x^4+561/6!*x^6-40415/8!*x^8...

A012229

cosh(arctan(tanh(x)))=1+1/2!*x^2-15/4!*x^4+561/6!*x^6-40415/8!*x^8...

Terms

    a(0) =1a(1) =1a(2) =-15a(3) =561a(4) =-40415a(5) =4825121a(6) =-866056815a(7) =218527875281

External references