sech(tan(arctanh(x)))=1-1/2!*x^2-11/4!*x^4-301/6!*x^6-14839/8!*x^8...

A012184

sech(tan(arctanh(x)))=1-1/2!*x^2-11/4!*x^4-301/6!*x^6-14839/8!*x^8...

Terms

    a(0) =1a(1) =-1a(2) =-11a(3) =-301a(4) =-14839a(5) =-1109881a(6) =-110852675a(7) =-12696026981

External references