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