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