sech(arcsin(sinh(x)))=1-1/2!*x^2-3/4!*x^4-21/6!*x^6-1543/8!*x^8...

A012110

sech(arcsin(sinh(x)))=1-1/2!*x^2-3/4!*x^4-21/6!*x^6-1543/8!*x^8...

Terms

    a(0) =1a(1) =-1a(2) =-3a(3) =-21a(4) =-1543a(5) =-139241a(6) =-17567883a(7) =-3247844861a(8) =-820544875023

External references