Comment by cbondurant

my immediate first thought is that I've never heard of the consecutive constraint before, or that if I have I have forgotten about it. I've only ever heard of a uniqueness constraint, that no number can be used twice, which still achieves the same goal of preventing filling every cell with exactly one number.

Then again, I do mostly remember this in terms of the yet unsolved magic-square-of-squares problem, not the standard magic square.