a(n) = (8*n)!/(n!*(2*n)!*(5*n)!).A391700a(n) = (8*n)!/(n!*(2*n)!*(5*n)!).Terms a(0) =1a(1) =168a(2) =120120a(3) =109830336a(4) =111767455800External referencesoeis: A391700