sech(tanh(x)*tan(x))=1-12/4!*x^4+2128/8!*x^8+3482688/12!*x^12...

A012675

sech(tanh(x)*tan(x))=1-12/4!*x^4+2128/8!*x^8+3482688/12!*x^12...

Terms

    a(0) =1a(1) =-12a(2) =2128a(3) =3482688a(4) =-28510476032

External references