sech(tan(x)*tan(x))=1-12/4!*x^4-480/6!*x^6-15792/8!*x^8...

A012395

sech(tan(x)*tan(x))=1-12/4!*x^4-480/6!*x^6-15792/8!*x^8...

Terms

    a(0) =1a(1) =0a(2) =-12a(3) =-480a(4) =-15792a(5) =387840a(6) =232592448a(7) =44951262720

External references