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