a(n) = ((n+1)!*(2*n+1)!/4) * [x^(2*n-2)] 1/sin(x)^2.

A080325

a(n) = ((n+1)!*(2*n+1)!/4) * [x^(2*n-2)] 1/sin(x)^2.

Terms

    a(0) =0a(1) =1a(2) =12a(3) =320a(4) =16128a(5) =1382400a(6) =186802176a(7) =37571788800

External references