tanh(sec(x)-sech(x))=2/2!*x^2-118/6!*x^6-29998/10!*x^10...

A013511

tanh(sec(x)-sech(x))=2/2!*x^2-118/6!*x^6-29998/10!*x^10...

Terms

    a(0) =2a(1) =-118a(2) =-29998a(3) =611334362

External references