a(n) = n! * binomial(n,5).A001807a(n) = n! * binomial(n,5).Terms a(0) =120a(1) =4320a(2) =105840a(3) =2257920a(4) =45722880a(5) =914457600a(6) =18441561600a(7) =379369267200External referencesoeis: A001807