Using all integers from 1 to 20, assign them into a 5 by 4 grid so that adjacent numbers (horizontally, vertically and diagonally) will differ by at least 4.
(In reply to computer solutions
I didn't try this by hand so I don't know how difficult that would be.
I'm curious if there are solutions with minimum difference 5 (or 6 etc.)
Posted by Jer
on 2016-02-14 15:30:09