| proposed by | Toby Walsh tw@cs.york.ac.uk |
We have a constraint that all diagonals sum to 38. That is, A+B+C = D+E+F+G = ... = Q+R+S = 38, A+D+H = B+E+I+M = ... = L+P+S = 38, C+G+L = B+F+K+P = ... = H+M+Q = 38.
The problem can be generalized to other sizes. This is the diameter 5 problem.