cos(sec(x)-sech(x))=1-12/4!*x^4-5152/8!*x^8-7351872/12!*x^12...

A013508

cos(sec(x)-sech(x))=1-12/4!*x^4-5152/8!*x^8-7351872/12!*x^12...

Terms

    a(0) =1a(1) =-12a(2) =-5152a(3) =-7351872a(4) =23844355328

External references