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