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

A000816

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

Terms

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

External references