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