Depicted below is one way to divide a 6x6 square into a four areas along the grid lines such that the division has 90 degree rotational symmetry.
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How many ways are there to quarter a square like this?
(In reply to
computer solution by Charlie)
Scaled up to 8x8 there are 1191 such patterns, or 1190/2+1 = 596, if reflections are eliminated. I only had to fix one bug in the program where I had hard coded a 3 instead of sz/2.

Posted by Charlie
on 20160329 16:08:03 