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