tanh(arctan(x)*tan(x))=2/2!*x^2-80/6!*x^6-2688/8!*x^8+18688/10!*x^10...

A012451

tanh(arctan(x)*tan(x))=2/2!*x^2-80/6!*x^6-2688/8!*x^8+18688/10!*x^10...

Terms

    a(0) =2a(1) =0a(2) =-80a(3) =-2688a(4) =18688a(5) =2928640a(6) =827766784a(7) =-52425949184

External references