Expansion of (sec(x/2)^2 + sech(x/2)^2)/2 in powers of x^4.

A090681

Expansion of (sec(x/2)^2 + sech(x/2)^2)/2 in powers of x^4.

Terms

    a(0) =1a(1) =1a(2) =31a(3) =5461a(4) =3202291a(5) =4722116521

External references