X ( 2 , 17 , 3 , 18 ) X ( 3 , 10 , 4 , 11 ) X ( 6 , 7 , 1 , 8 ) X ( 8 , 1 , 9 , 2 ) X ( 9 , 16 , 10 , 17 ) X ( 12 , 5 , 13 , 6 ) X ( 13 , 20 , 14 , 21 ) X ( 15 , 22 , 16 , 7 ) X ( 18 , 11 , 19 , 12 ) X ( 19 , 4 , 20 , 5 ) X ( 21 , 14 , 22 , 15 ) {\displaystyle X(2,17,3,18)X(3,10,4,11)X(6,7,1,8)X(8,1,9,2)X(9,16,10,17)X(12,5,13,6)X(13,20,14,21)X(15,22,16,7)X(18,11,19,12)X(19,4,20,5)X(21,14,22,15)}
