arctan(sec(x)-sech(x))=2/2!*x^2-118/6!*x^6+211922/10!*x^10...

A013507

arctan(sec(x)-sech(x))=2/2!*x^2-118/6!*x^6+211922/10!*x^10...

Terms

    a(0) =2a(1) =-118a(2) =211922a(3) =-2213888038

External references