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 From the computer -semi-spoiler
Since my comment at that location re 5-order Q-Basic compilation I have a program running, been going for 24 hours and still hasn't offered a result.
My computer is currently offering:
1 1 1 9 7
1 0 0 0 7
3 3 6 1 7
* * * * *
* * * * *
The program is working upwards so there is no guarantee that the three primes, which are also reversible, will be intact.
Oops 3 3 6 2 3 !
I think the compiled program has a finish within our life time, but I'll try to let it run for 7 days to see if there is an outcome.
That said, I look at the date Ady gave as reference, 1968! One must ask how the solutions he has telegraphed in comments came into being, computers were still big but just how powerful?
Posted by brianjn
on 2012-01-19 08:11:29