sech(arcsin(arctan(x)))=1-1/2!*x^2+9/4!*x^4-249/6!*x^6+13297/8!*x^8...

A012098

sech(arcsin(arctan(x)))=1-1/2!*x^2+9/4!*x^4-249/6!*x^6+13297/8!*x^8...

Terms

    a(0) =1a(1) =-1a(2) =9a(3) =-249a(4) =13297a(5) =-1175761a(6) =154625721a(7) =-28328562313

External references