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