tan(tanh(x)*arctan(x))=2/2!*x^2-16/4!*x^4+560/6!*x^6-39296/8!*x^8...

A012679

tan(tanh(x)*arctan(x))=2/2!*x^2-16/4!*x^4+560/6!*x^6-39296/8!*x^8...

Terms

    a(0) =2a(1) =-16a(2) =560a(3) =-39296a(4) =4526848a(5) =-774871040a(6) =184332195840

External references