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