sec(sin(tanh(x))) = 1+1/2!*x^2-7/4!*x^4+73/6!*x^6+209/8!*x^8...

A012049

sec(sin(tanh(x))) = 1+1/2!*x^2-7/4!*x^4+73/6!*x^6+209/8!*x^8...

Terms

    a(0) =1a(1) =1a(2) =-7a(3) =73a(4) =209a(5) =-144271a(6) =16935049a(7) =-1681509255a(8) =121927140641

External references