a(n) = n! * (n+1)! * (n+2)! / (2! * 3!).A010797a(n) = n! * (n+1)! * (n+2)! / (2! * 3!).Terms a(0) =1a(1) =24a(2) =1440a(3) =172800a(4) =36288000a(5) =12192768000External referencesoeis: A010797