Turtle Backs

Howdy tuners!

I was just skimming through the math stuff on the list and was reminded of a
puzzle/pattern that fascinates me. It's the old tic-tac-toe (or turtle back)
number pattern that adds up to the same thing in all directions, like this...

8 1 6
3 5 7
4 9 2
-------------
15's

expanded...

17 24 1 8 15
23 5 7 14 16
4 6 13 20 22
10 12 19 21 3
11 18 25 2 9
---------------------------
65's

It always fascinates me because of how easy it is to generate these matrices
if you know the pattern. Just as long as it is square and has an odd length
on its side, it works, and it is possible to generate infinitely huge (and
seemingly complex (to me anyway)) matrices.

It occurred to me that there are some really cool tunings in there.

Has anybody done any work with something similar?
Am I way out in left field? (I wouldn't know if i was/am)

regards,
andy