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