cos(tan(arctanh(x)))=1-1/2!*x^2-15/4!*x^4-561/6!*x^6-38623/8!*x^8...

A012178

cos(tan(arctanh(x)))=1-1/2!*x^2-15/4!*x^4-561/6!*x^6-38623/8!*x^8...

Terms

    a(0) =1a(1) =-1a(2) =-15a(3) =-561a(4) =-38623a(5) =-4206881a(6) =-661302639a(7) =-140958927825

External references