sech(arcsinh(x)*cos(x))=1-1/2!*x^2+21/4!*x^4-765/6!*x^6+53193/8!*x^8...

A012645

sech(arcsinh(x)*cos(x))=1-1/2!*x^2+21/4!*x^4-765/6!*x^6+53193/8!*x^8...

Terms

    a(0) =1a(1) =-1a(2) =21a(3) =-765a(4) =53193a(5) =-6008025a(6) =993328413a(7) =-226691205013

External references