E.g.f.: cos(x)^2 / cos(2x) = Sum_{n >= 0} a(n) * x^(2n) / (2n)!.

A000819

E.g.f.: cos(x)^2 / cos(2x) = Sum_{n >= 0} a(n) * x^(2n) / (2n)!.

Terms

    a(0) =1a(1) =2a(2) =40a(3) =1952a(4) =177280a(5) =25866752a(6) =5535262720

External references