sech(arcsin(arcsin(x)))=1-1/2!*x^2-3/4!*x^4-69/6!*x^6-3335/8!*x^8...

A012074

sech(arcsin(arcsin(x)))=1-1/2!*x^2-3/4!*x^4-69/6!*x^6-3335/8!*x^8...

Terms

    a(0) =1a(1) =-1a(2) =-3a(3) =-69a(4) =-3335a(5) =-289801a(6) =-39612939a(7) =-7845054541

External references