E.g.f.: -log(cos(x)*cos(x)) (even powers only).

A012509

E.g.f.: -log(cos(x)*cos(x)) (even powers only).

Terms

    a(0) =0a(1) =2a(2) =4a(3) =32a(4) =544a(5) =15872a(6) =707584a(7) =44736512a(8) =3807514624a(9) =419730685952

External references