a(n) = (Pi/2)*(2*n+1)!*binomial(2*n+1, (2*n+1)/2).

A329928

a(n) = (Pi/2)*(2*n+1)!*binomial(2*n+1, (2*n+1)/2).

Terms

    a(0) =2a(1) =32a(2) =2048a(3) =294912a(4) =75497472a(5) =30198988800

External references