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