sech(arcsin(arcsinh(x)))=1-1/2!*x^2+5/4!*x^4-109/6!*x^6+4073/8!*x^8...

A012122

sech(arcsin(arcsinh(x)))=1-1/2!*x^2+5/4!*x^4-109/6!*x^6+4073/8!*x^8...

Terms

    a(0) =1a(1) =-1a(2) =5a(3) =-109a(4) =4073a(5) =-295161a(6) =30105261a(7) =-4622444709a(8) =920180967249

External references