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