Working in columns, the sum of the numbers in each column is always 14.
The numbers in each row and column add up to 15.
Moving from left to right, numbers increase by 2,3,4 and 5.
In each square of the diagram, the sum of the numbers is always 22.
Moving clockwise, around alternate segments in the chain, one sequence decreases by 1, 2, 3 and 4 each time, while the other increases by 2, 3, 4 and 5.