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