X ( 1 , 21 , 2 , 20 ) X ( 3 , 23 , 4 , 22 ) X ( 5 , 25 , 6 , 24 ) X ( 7 , 27 , 8 , 26 ) X ( 9 , 29 , 10 , 28 ) X ( 11 , 31 , 12 , 30 ) X ( 13 , 33 , 14 , 32 ) X ( 15 , 35 , 16 , 34 ) X ( 17 , 37 , 18 , 36 ) X ( 19 , 1 , 20 , 38 ) X ( 21 , 3 , 22 , 2 ) X ( 23 , 5 , 24 , 4 ) X ( 25 , 7 , 26 , 6 ) X ( 27 , 9 , 28 , 8 ) X ( 29 , 11 , 30 , 10 ) X ( 31 , 13 , 32 , 12 ) X ( 33 , 15 , 34 , 14 ) X ( 35 , 17 , 36 , 16 ) X ( 37 , 19 , 38 , 18 ) {\displaystyle X(1,21,2,20)X(3,23,4,22)X(5,25,6,24)X(7,27,8,26)X(9,29,10,28)X(11,31,12,30)X(13,33,14,32)X(15,35,16,34)X(17,37,18,36)X(19,1,20,38)X(21,3,22,2)X(23,5,24,4)X(25,7,26,6)X(27,9,28,8)X(29,11,30,10)X(31,13,32,12)X(33,15,34,14)X(35,17,36,16)X(37,19,38,18)}
