Even coefficients in expansion of e.g.f. sec(arcsin(arctan(x))).

A012097

Even coefficients in expansion of e.g.f. sec(arcsin(arctan(x))).

Terms

    a(0) =1a(1) =1a(2) =1a(3) =49a(4) =-447a(5) =78561a(6) =-5655231a(7) =1014069393a(8) =-187639949439

External references