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