1317254400domain: NAppears in sequencesLah numbers: a(n) = n! * binomial(n-1, 4)/5!.at n=7A001777a(n) = 3*n*n!.at n=11A052673a(1) = 1, a(2) = 2; for n>2, a(n) = 3*(n-2)*(n-2)!.at n=12A083746