Let n be an integer.

Arrange the first n^2 odd numbers in a square n on a side, left-to-right and top-to-bottom, like so (n=3):

1 3 5

7 9 11

13 15 17

Regardless of what n you chose, the following will be true:

The sum of the first row is n^2

The sum of either diagonal (from one corner to the other) is n^3

The sum of all the numbers in the square is n^4