arctanh(sec(x)-sech(x))=2/2!*x^2+362/6!*x^6+1441682/10!*x^10...

A013512

arctanh(sec(x)-sech(x))=2/2!*x^2+362/6!*x^6+1441682/10!*x^10...

Terms

    a(0) =2a(1) =362a(2) =1441682a(3) =32555086202

External references