In a 4x4 magic square all rows, columns and the two main diagonals are distinct 4-digit prime numbers when read in either direction.
Create such a square.
Bonus (d4): same for order-5 magic square and 5-digit primes.
L. E. Card,Patterns in Primes, JRM 1:2, 1968, pp .93-99,
(In reply to re: From the computer -semi-spoiler
It is something like 55 hours after executing my program (which was compiled as a C++ EXE, I have had one solution set returned but the program is till running.
With this solution:
1 1 1 9 7
1 0 0 0 7
9 0 0 2 3
3 7 9 6 3
9 9 1 3 9
none of the digits within the top two rows have change since my prior post, I'm not sure how much longer I'm prepared to let this run.
I accidentally 'killed' the program by ordering a computer shut-down but the damage had been done by the time I hit Cancel! Considering the runtime to the point above (and possible some 8 hours afterwards I'm not going there again.
Edited on January 21, 2012, 7:01 am
Posted by brianjn
on 2012-01-20 18:38:42