sec(tanh(x)*arctan(x))=1+12/4!*x^4-480/6!*x^6+35280/8!*x^8...

A012686

sec(tanh(x)*arctan(x))=1+12/4!*x^4-480/6!*x^6+35280/8!*x^8...

Terms

    a(0) =1a(1) =0a(2) =12a(3) =-480a(4) =35280a(5) =-4208640a(6) =737643456a(7) =-178203637248

External references