cos(sec(x)*arctan(x))=1-1/2!*x^2-3/4!*x^4-165/6!*x^6+1337/8!*x^8...

A012806

cos(sec(x)*arctan(x))=1-1/2!*x^2-3/4!*x^4-165/6!*x^6+1337/8!*x^8...

Terms

    a(0) =1a(1) =-1a(2) =-3a(3) =-165a(4) =1337a(5) =-356745a(6) =31874997a(7) =-5714452653

External references