X ( 1 , 4 , 2 , 5 ) X ( 3 , 9 , 4 , 8 ) X ( 5 , 10 , 6 , 11 ) X ( 6 , 15 , 7 , 16 ) X ( 9 , 3 , 10 , 2 ) X ( 12 , 18 , 13 , 17 ) X ( 14 , 7 , 15 , 8 ) X ( 16 , 12 , 17 , 11 ) X ( 18 , 14 , 1 , 13 ) {\displaystyle X(1,4,2,5)X(3,9,4,8)X(5,10,6,11)X(6,15,7,16)X(9,3,10,2)X(12,18,13,17)X(14,7,15,8)X(16,12,17,11)X(18,14,1,13)}
