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