A sturdy square (akin to a magic square) is an arrangement of the integers 1 to \$N^2\$ on an \$N\$ by \$N\$ grid such that every 2 by 2 subgrid has the same sum.
For example, for \$N = 3\$ one sturdy square is
1 5 3
9 8 7
4 2 6
because the four 2 by 2 subgrids
1 5
9 8
5 3
8 7
9 8
4 2
8 7
2 6
all sum to the same amount, 23:
$$23 = 1 + 5 + 9 + 8 = 5 + 3 + 8 + 7 = 9 + 8 + 4 + 2 = 8 + 7 + 2 + 6$$
Now there are sturdy squares for higher values of N and even rectangular versions but your only task in this challenge is to output all possible 3 by 3 sturdy squares. There are exactly 376 distinct 3 by 3 sturdy squares, including those that are reflections or rotations of others, and not all of them have the same sum of 23.
Write a program or function that takes no input but prints or returns a string of all 376 sturdy squares in any order, separated by empty lines, with up to two optional trailing newlines. Each square should consist of three lines of three space separated nonzero decimal digits.
Here is a valid output example:
1 5 3
9 8 7
4 2 6
1 5 6
8 7 3
4 2 9
1 5 6
8 9 3
2 4 7
1 5 7
9 6 3
2 4 8
1 6 2
8 9 7
4 3 5
1 6 2
9 7 8
4 3 5
1 6 3
9 8 7
2 5 4
1 6 7
8 5 2
3 4 9
1 6 7
9 4 3
2 5 8
1 7 2
9 4 8
5 3 6
1 7 2
9 6 8
3 5 4
1 7 4
8 3 5
6 2 9
1 7 4
9 2 6
5 3 8
1 7 6
9 2 4
3 5 8
1 8 2
5 9 4
6 3 7
1 8 3
6 5 4
7 2 9
1 8 3
9 2 7
4 5 6
1 8 4
5 7 2
6 3 9
1 8 4
6 9 3
2 7 5
1 8 4
9 3 6
2 7 5
1 8 6
7 3 2
4 5 9
1 9 2
5 6 4
7 3 8
1 9 2
6 4 5
7 3 8
1 9 2
6 8 5
3 7 4
1 9 2
8 3 7
4 6 5
1 9 3
7 2 5
6 4 8
1 9 3
7 6 5
2 8 4
1 9 4
5 8 2
3 7 6
1 9 4
6 7 3
2 8 5
1 9 4
8 2 5
3 7 6
1 9 5
7 2 3
4 6 8
1 9 5
7 4 3
2 8 6
2 3 5
9 8 6
4 1 7
2 3 6
9 7 5
4 1 8
2 4 3
8 9 7
5 1 6
2 4 3
9 7 8
5 1 6
2 4 6
7 8 3
5 1 9
2 4 7
8 9 3
1 5 6
2 4 8
9 6 3
1 5 7
2 5 3
9 4 8
6 1 7
2 5 4
9 3 7
6 1 8
2 5 4
9 8 7
1 6 3
2 5 7
6 8 1
4 3 9
2 5 7
6 9 1
3 4 8
2 5 8
7 6 1
3 4 9
2 5 8
9 4 3
1 6 7
2 6 1
7 9 8
5 3 4
2 6 1
8 7 9
5 3 4
2 6 3
5 9 4
7 1 8
2 6 4
5 8 3
7 1 9
2 6 7
9 1 4
3 5 8
2 6 8
7 4 1
3 5 9
2 7 1
8 4 9
6 3 5
2 7 1
8 6 9
4 5 3
2 7 3
5 6 4
8 1 9
2 7 3
6 4 5
8 1 9
2 7 3
9 1 8
5 4 6
2 7 5
4 8 1
6 3 9
2 7 5
6 9 3
1 8 4
2 7 5
9 3 6
1 8 4
2 8 1
4 9 5
7 3 6
2 8 4
7 6 5
1 9 3
2 8 5
4 9 1
3 7 6
2 8 5
6 7 3
1 9 4
2 8 6
7 4 3
1 9 5
2 9 1
4 6 5
8 3 7
2 9 1
5 4 6
8 3 7
2 9 1
5 8 6
4 7 3
2 9 1
7 3 8
5 6 4
2 9 3
6 1 5
7 4 8
2 9 4
3 7 1
6 5 8
2 9 4
3 8 1
5 6 7
2 9 5
4 7 1
3 8 6
2 9 5
7 1 4
3 8 6
2 9 6
5 3 1
4 7 8
2 9 6
5 4 1
3 8 7
3 2 5
9 8 7
4 1 6
3 2 6
8 9 5
4 1 7
3 2 7
9 6 5
4 1 8
3 4 2
7 9 8
6 1 5
3 4 2
8 7 9
6 1 5
3 4 5
9 2 7
6 1 8
3 4 8
6 9 1
2 5 7
3 4 9
7 6 1
2 5 8
3 4 9
8 5 2
1 6 7
3 5 1
7 8 9
6 2 4
3 5 2
8 4 9
7 1 6
3 5 4
9 1 8
6 2 7
3 5 4
9 6 8
1 7 2
3 5 8
9 1 4
2 6 7
3 5 8
9 2 4
1 7 6
3 5 9
7 4 1
2 6 8
3 6 1
7 8 9
4 5 2
3 6 2
4 9 5
8 1 7
3 6 8
7 1 2
4 5 9
3 7 2
4 6 5
9 1 8
3 7 2
5 4 6
9 1 8
3 7 2
8 1 9
6 4 5
3 7 4
6 1 5
8 2 9
3 7 4
6 8 5
1 9 2
3 7 6
4 9 1
2 8 5
3 7 6
5 8 2
1 9 4
3 7 6
8 2 5
1 9 4
3 8 1
4 5 6
9 2 7
3 8 1
7 2 9
6 5 4
3 8 4
2 9 1
6 5 7
3 8 6
4 7 1
2 9 5
3 8 6
7 1 4
2 9 5
3 8 7
5 4 1
2 9 6
3 9 1
5 2 7
8 4 6
3 9 1
5 6 7
4 8 2
3 9 2
5 1 6
8 4 7
3 9 4
2 6 1
7 5 8
3 9 4
2 8 1
5 7 6
3 9 6
4 2 1
5 7 8
3 9 6
5 1 2
4 8 7
4 1 6
9 8 7
3 2 5
4 1 7
8 9 5
3 2 6
4 1 7
9 8 6
2 3 5
4 1 8
9 6 5
3 2 7
4 1 8
9 7 5
2 3 6
4 2 6
9 8 7
1 5 3
4 2 7
6 9 3
5 1 8
4 2 7
9 3 6
5 1 8
4 2 8
7 6 3
5 1 9
4 2 9
8 7 3
1 5 6
4 3 5
8 9 7
1 6 2
4 3 5
9 2 8
6 1 7
4 3 5
9 7 8
1 6 2
4 3 7
5 8 2
6 1 9
4 3 7
8 2 5
6 1 9
4 3 7
9 1 6
5 2 8
4 3 9
6 8 1
2 5 7
4 5 2
7 3 9
8 1 6
4 5 2
7 8 9
3 6 1
4 5 3
8 1 9
7 2 6
4 5 3
8 6 9
2 7 1
4 5 6
3 8 1
7 2 9
4 5 6
9 2 7
1 8 3
4 5 9
7 1 2
3 6 8
4 5 9
7 3 2
1 8 6
4 6 2
3 8 5
9 1 7
4 6 5
2 9 1
7 3 8
4 6 5
8 3 7
1 9 2
4 6 8
7 2 3
1 9 5
4 7 1
5 3 8
9 2 6
4 7 1
6 2 9
8 3 5
4 7 3
5 1 6
9 2 8
4 7 3
5 8 6
2 9 1
4 7 5
2 6 1
8 3 9
4 7 8
5 3 1
2 9 6
4 8 1
2 7 5
9 3 6
4 8 1
3 9 6
5 7 2
4 8 1
6 3 9
5 7 2
4 8 2
5 6 7
3 9 1
4 8 3
1 9 2
7 5 6
4 8 6
3 2 1
7 5 9
4 8 7
5 1 2
3 9 6
4 9 1
2 8 5
6 7 3
4 9 1
3 7 6
5 8 2
4 9 1
5 2 8
6 7 3
4 9 2
1 7 3
8 5 6
4 9 2
1 8 3
7 6 5
4 9 3
1 6 2
8 5 7
4 9 3
1 8 2
6 7 5
4 9 5
2 3 1
7 6 8
4 9 5
3 1 2
7 6 8
4 9 6
3 2 1
5 8 7
5 1 6
8 9 7
2 4 3
5 1 6
9 7 8
2 4 3
5 1 8
6 9 3
4 2 7
5 1 8
9 3 6
4 2 7
5 1 9
7 6 3
4 2 8
5 1 9
7 8 3
2 4 6
5 2 3
7 8 9
6 1 4
5 2 8
7 3 4
6 1 9
5 2 8
9 1 6
4 3 7
5 3 2
6 8 9
7 1 4
5 3 4
7 9 8
2 6 1
5 3 4
8 2 9
7 1 6
5 3 4
8 7 9
2 6 1
5 3 6
9 4 8
1 7 2
5 3 8
4 7 1
6 2 9
5 3 8
7 1 4
6 2 9
5 3 8
9 2 6
1 7 4
5 4 3
7 2 9
8 1 6
5 4 6
3 7 2
8 1 9
5 4 6
9 1 8
2 7 3
5 6 4
1 9 2
8 3 7
5 6 4
7 3 8
2 9 1
5 6 7
3 8 1
2 9 4
5 7 2
1 8 4
9 3 6
5 7 2
3 9 6
4 8 1
5 7 2
6 3 9
4 8 1
5 7 4
1 6 2
9 3 8
5 7 6
2 3 1
8 4 9
5 7 6
2 8 1
3 9 4
5 7 6
3 1 2
8 4 9
5 7 8
4 2 1
3 9 6
5 8 2
1 9 4
6 7 3
5 8 2
3 7 6
4 9 1
5 8 7
3 2 1
4 9 6
5 9 1
3 2 7
8 6 4
5 9 1
3 4 7
6 8 2
5 9 2
1 7 4
6 8 3
5 9 2
4 1 7
6 8 3
5 9 4
1 3 2
8 6 7
5 9 4
2 1 3
8 6 7
6 1 4
7 8 9
5 2 3
6 1 5
7 9 8
3 4 2
6 1 5
8 7 9
3 4 2
6 1 7
9 2 8
4 3 5
6 1 7
9 4 8
2 5 3
6 1 8
9 2 7
3 4 5
6 1 8
9 3 7
2 5 4
6 1 9
5 8 2
4 3 7
6 1 9
7 3 4
5 2 8
6 1 9
8 2 5
4 3 7
6 2 3
5 9 8
7 1 4
6 2 4
7 8 9
3 5 1
6 2 7
9 1 8
3 5 4
6 2 8
5 4 3
7 1 9
6 2 9
4 7 1
5 3 8
6 2 9
7 1 4
5 3 8
6 2 9
8 3 5
1 7 4
6 3 2
5 7 9
8 1 4
6 3 5
8 4 9
2 7 1
6 3 7
5 2 4
8 1 9
6 3 7
5 9 4
1 8 2
6 3 9
4 8 1
2 7 5
6 3 9
5 7 2
1 8 4
6 4 2
3 8 7
9 1 5
6 4 5
2 7 3
9 1 8
6 4 5
8 1 9
3 7 2
6 4 8
7 2 5
1 9 3
6 5 1
3 7 8
9 2 4
6 5 1
3 9 8
7 4 2
6 5 4
1 8 3
9 2 7
6 5 4
7 2 9
3 8 1
6 5 7
2 4 1
8 3 9
6 5 7
2 9 1
3 8 4
6 5 8
3 2 1
7 4 9
6 5 8
3 7 1
2 9 4
6 7 1
4 2 9
8 5 3
6 7 3
1 9 4
5 8 2
6 7 3
2 8 5
4 9 1
6 7 3
5 2 8
4 9 1
6 7 5
1 3 2
9 4 8
6 7 5
1 8 2
4 9 3
6 7 5
2 1 3
9 4 8
6 8 1
2 3 7
9 5 4
6 8 2
3 4 7
5 9 1
6 8 3
1 7 4
5 9 2
6 8 3
4 1 7
5 9 2
6 8 4
1 2 3
9 5 7
6 9 2
1 3 5
8 7 4
6 9 2
1 4 5
7 8 3
6 9 3
1 2 4
8 7 5
6 9 3
2 1 5
7 8 4
6 9 4
1 2 3
7 8 5
7 1 4
5 9 8
6 2 3
7 1 4
6 8 9
5 3 2
7 1 6
8 2 9
5 3 4
7 1 6
8 4 9
3 5 2
7 1 8
5 9 4
2 6 3
7 1 9
5 4 3
6 2 8
7 1 9
5 8 3
2 6 4
7 2 3
5 6 9
8 1 4
7 2 4
3 9 6
8 1 5
7 2 4
6 3 9
8 1 5
7 2 6
8 1 9
4 5 3
7 2 9
3 8 1
4 5 6
7 2 9
6 5 4
1 8 3
7 3 4
2 8 5
9 1 6
7 3 4
5 2 8
9 1 6
7 3 4
6 1 9
8 2 5
7 3 6
4 2 5
9 1 8
7 3 6
4 9 5
2 8 1
7 3 8
2 9 1
4 6 5
7 3 8
5 6 4
1 9 2
7 3 8
6 4 5
1 9 2
7 4 2
3 9 8
6 5 1
7 4 8
6 1 5
2 9 3
7 4 9
3 2 1
6 5 8
7 5 1
3 6 9
8 4 2
7 5 2
1 8 6
9 3 4
7 5 2
1 9 6
8 4 3
7 5 6
1 4 2
9 3 8
7 5 6
1 9 2
4 8 3
7 5 8
2 6 1
3 9 4
7 5 9
3 2 1
4 8 6
7 6 1
2 5 8
9 4 3
7 6 1
3 4 9
8 5 2
7 6 2
4 1 9
8 5 3
7 6 5
1 8 3
4 9 2
7 6 8
2 3 1
4 9 5
7 6 8
3 1 2
4 9 5
7 8 3
1 4 5
6 9 2
7 8 4
2 1 5
6 9 3
7 8 5
1 2 3
6 9 4
8 1 4
5 6 9
7 2 3
8 1 4
5 7 9
6 3 2
8 1 5
3 9 6
7 2 4
8 1 5
6 3 9
7 2 4
8 1 6
7 2 9
5 4 3
8 1 6
7 3 9
4 5 2
8 1 7
4 9 5
3 6 2
8 1 9
3 7 2
5 4 6
8 1 9
5 2 4
6 3 7
8 1 9
5 6 4
2 7 3
8 1 9
6 4 5
2 7 3
8 2 4
3 6 7
9 1 5
8 2 5
4 3 7
9 1 6
8 2 5
6 1 9
7 3 4
8 2 6
3 4 5
9 1 7
8 2 9
6 1 5
3 7 4
8 3 5
1 7 4
9 2 6
8 3 5
4 1 7
9 2 6
8 3 5
6 2 9
4 7 1
8 3 7
1 9 2
5 6 4
8 3 7
4 6 5
2 9 1
8 3 7
5 4 6
2 9 1
8 3 9
2 4 1
6 5 7
8 3 9
2 6 1
4 7 5
8 4 2
3 6 9
7 5 1
8 4 3
1 9 6
7 5 2
8 4 6
5 2 7
3 9 1
8 4 7
5 1 6
3 9 2
8 4 9
2 3 1
5 7 6
8 4 9
3 1 2
5 7 6
8 5 2
1 6 7
9 4 3
8 5 2
3 4 9
7 6 1
8 5 3
4 1 9
7 6 2
8 5 3
4 2 9
6 7 1
8 5 6
1 2 3
9 4 7
8 5 6
1 7 3
4 9 2
8 5 7
1 6 2
4 9 3
8 6 2
1 4 7
9 5 3
8 6 3
2 1 7
9 5 4
8 6 4
3 2 7
5 9 1
8 6 7
1 3 2
5 9 4
8 6 7
2 1 3
5 9 4
8 7 4
1 3 5
6 9 2
8 7 5
1 2 4
6 9 3
9 1 5
3 6 7
8 2 4
9 1 5
3 8 7
6 4 2
9 1 6
2 8 5
7 3 4
9 1 6
4 3 7
8 2 5
9 1 6
5 2 8
7 3 4
9 1 7
3 4 5
8 2 6
9 1 7
3 8 5
4 6 2
9 1 8
2 7 3
6 4 5
9 1 8
4 2 5
7 3 6
9 1 8
4 6 5
3 7 2
9 1 8
5 4 6
3 7 2
9 2 4
3 7 8
6 5 1
9 2 6
1 7 4
8 3 5
9 2 6
4 1 7
8 3 5
9 2 6
5 3 8
4 7 1
9 2 7
1 8 3
6 5 4
9 2 7
4 5 6
3 8 1
9 2 8
5 1 6
4 7 3
9 3 4
1 8 6
7 5 2
9 3 6
1 8 4
5 7 2
9 3 6
2 7 5
4 8 1
9 3 8
1 4 2
7 5 6
9 3 8
1 6 2
5 7 4
9 4 3
1 6 7
8 5 2
9 4 3
2 5 8
7 6 1
9 4 7
1 2 3
8 5 6
9 4 8
1 3 2
6 7 5
9 4 8
2 1 3
6 7 5
9 5 3
1 4 7
8 6 2
9 5 4
2 1 7
8 6 3
9 5 4
2 3 7
6 8 1
9 5 7
1 2 3
6 8 4
Your program must produce these same 376 sturdy squares, just not necessarily in this order. The output does not need to be deterministic, i.e. you could output them in different orders on different runs as long as they are all there.
The shortest code in bytes wins.
The topic of sturdy squares originated with this chat message of mine which led to a large amount of discussion on their properties and how to generate them. Props to Peter Taylor, feersum, and Sp3000 for continuing the discussion, and especially to El'endia Starman for drafting a corresponding OEIS sequence.
5 7 3\n\n
, so there is one blank line after the last square. Is that admissible? \$\endgroup\$