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