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