sec(sec(x)*arctanh(x))=1+1/2!*x^2+25/4!*x^4+1225/6!*x^6+108113/8!*x^8...

A012851

sec(sec(x)*arctanh(x))=1+1/2!*x^2+25/4!*x^4+1225/6!*x^6+108113/8!*x^8...

Terms

    a(0) =1a(1) =1a(2) =25a(3) =1225a(4) =108113a(5) =15283505a(6) =3167087273a(7) =904365439289

External references