X ( 1 , 17 , 2 , 16 ) X ( 3 , 19 , 4 , 18 ) X ( 5 , 21 , 6 , 20 ) X ( 7 , 23 , 8 , 22 ) X ( 9 , 25 , 10 , 24 ) X ( 11 , 27 , 12 , 26 ) X ( 13 , 29 , 14 , 28 ) X ( 15 , 1 , 16 , 30 ) X ( 17 , 3 , 18 , 2 ) X ( 19 , 5 , 20 , 4 ) X ( 21 , 7 , 22 , 6 ) X ( 23 , 9 , 24 , 8 ) X ( 25 , 11 , 26 , 10 ) X ( 27 , 13 , 28 , 12 ) X ( 29 , 15 , 30 , 14 ) {\displaystyle X(1,17,2,16)X(3,19,4,18)X(5,21,6,20)X(7,23,8,22)X(9,25,10,24)X(11,27,12,26)X(13,29,14,28)X(15,1,16,30)X(17,3,18,2)X(19,5,20,4)X(21,7,22,6)X(23,9,24,8)X(25,11,26,10)X(27,13,28,12)X(29,15,30,14)}