1244678400domain: NAppears in sequencesa(n) = (n*n!)^2.at n=6A176128a(n) = [n/2]!*[(n+1)/2]!*C([n/2],1)*C([(n+1)/2],1).at n=13A226282a(n) = [n/2]!*[(n+1)/2]!*C([n/2],6)*C([(n+1)/2],6).at n=13A226287