sech(arctan(x)*tan(x))=1-12/4!*x^4-560/8!*x^8+241920/10!*x^10...

A012455

sech(arctan(x)*tan(x))=1-12/4!*x^4-560/8!*x^8+241920/10!*x^10...

Terms

    a(0) =1a(1) =0a(2) =-12a(3) =0a(4) =-560a(5) =241920a(6) =-8750016a(7) =1727165440a(8) =-426305201920

External references