It would appear that there are an awful lot of these out there, so perhaps the challange should be to find a square with the lowest standard deviation of column/row/diagonal totals.
I'll start the ball rolling with a slightly modified version of the last square I posted, with an s.d. of 84.51:
Code:
239
/
/
/
3, 5, 7, 11, 17 --- 43
13, 19, 29, 23, 43 --- 127
31, 67, 61, 47, 71 --- 277
53, 59, 89, 73, 37 --- 311
79, 83, 41, 97, 101 --- 401
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179 233 227 251 269 257