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