a(n) = 4^n*binomial(2*n+1, n).

Terms

a(0) =1a(1) =12a(2) =160a(3) =2240a(4) =32256a(5) =473088a(6) =7028736a(7) =105431040a(8) =1593180160a(9) =24216338432a(10) =369849532416