# Rallier des Ourmes

A somehow more complicated method was found by Jean-Joseph Rallier des Ourmes, who first placed the median number in the central field of the square, including the number 1 below and the order n to the left of the center. The cells that are symmetrical to the center are then filled with their complementary numbers.

Now the remaining cells in the middle row are filled. Starting from the number 25 in the center of the square, every second cell is now filled. The current number is decreased by n − 1, progressing to the right, but increased by n − 1, progressing to the left. The same procedure is followed by starting from the left or right neighboring number (7 or 43) of the central cell. However, now you only move in one direction.

The same procedure is followed with the middle column, except that the numbers are decreased by n + 1 upwards, but increased downwards by n + 1. The result is shown for order n=7.

•  49 7 25 43 1
•  41 17 49 13 31 7 25 43 19 37 1 33 9

Starting from the numbers in the middle row or column, the empty fields of the square are now filled diagonally according to the diagram. On the top right, the current number is always decreased by −n, on the other hand it is increased by n on the bottom left. Decreased by −n to the top left and increased by +1 to the bottom right.

The following figure shows magic squares of orders n=7 and n=9 constructed by this method.

•  22 47 16 41 10 35 4 5 23 48 17 42 11 29 30 6 24 49 18 36 12 13 31 7 25 43 19 37 38 14 32 1 26 44 20 21 39 8 33 2 27 45 46 15 40 9 34 3 28
•  37 78 29 70 21 62 13 54 5 6 38 79 30 71 22 63 14 46 47 7 39 80 31 72 23 55 15 16 48 8 40 81 32 64 24 56 57 17 49 9 41 73 33 65 25 26 58 18 50 1 42 74 34 66 67 27 59 10 51 2 43 75 35 36 68 19 60 11 52 3 44 76 77 28 69 20 61 12 53 4 45