a(n) = n! * 4^binomial(n, 2).A376868a(n) = n! * 4^binomial(n, 2).Terms a(0) =1a(1) =1a(2) =8a(3) =384a(4) =98304a(5) =125829120a(6) =773094113280External referencesoeis: A376868