Hey VQC, I understand what you're trying to do by giving us as much ability to solve this as we can before you potentially post it yourself, but I've got to ask. This stuff about diagonals and x=f-1 seems to have thrown everybody off significantly. Were we meant to have figured that out ourselves? We still don't seem to know what to do with either clue. Considering you've said many times that we have enough information to figure this out, did we have enough information to figure out that diagonals and x=f-1 are significant?
>Think about the values in 0,1 and 0,1.
Well, obviously you meant to mention more than just (0,1), but in the absence of that other cell, here's the clue about (0,1) from Grid Patterns:
In cell (0,1), e is zero, so all cs are perfect squares (the smaller square (x+n)(x+n) being 0). These values of c ALL appear in (0,0) but they also ALL have more than one way to arrange their factors. The factors this time produce an n value of 1. 4x4 = 16 can be arranged as 2x8 = 16, which is equal to 5x5 - 3x3. Notice that all the values of a in this cell are also each twice the value of a perfect square.
1+1 = 2
4+4 = 8
9+9 = 18
Notice that all the values of d for this cell also follow a pattern:
2x(1x2) = 4
2x(2x3) = 12
2x(3x4) = 24
If that other cell was meant to be (1,1), here's another potentially relevant clue from Grid Patterns:
Each value of a in cell (1,1) is also the long side of an integer right angled triangle.