a(n) = Product_{k=0..n} (3*k+2)^(n-k).A263417a(n) = Product_{k=0..n} (3*k+2)^(n-k).Terms a(0) =1a(1) =2a(2) =20a(3) =1600a(4) =1408000a(5) =17346560000External referencesoeis: A263417