sec(arctanh(x)+arctan(x))=1+4/2!*x^2+80/4!*x^4+4480/6!*x^6...

A013180

sec(arctanh(x)+arctan(x))=1+4/2!*x^2+80/4!*x^4+4480/6!*x^6...

Terms

    a(0) =1a(1) =4a(2) =80a(3) =4480a(4) =462080a(5) =77248000a(6) =18902835200

External references