pr.probability – Probability of 3 character code occuring thrice in 8*8 grid

I need to determine how certain a 3 character code appearing in order, 3 times, in an 8 X 8 grid is of being deliberate. Any 3 character sequence, in any direction and shape but not diagonal, so a horizontal or vertical row of 3 or an L shape. So for a grid width G we have (G – 3) * G * 2 rows and columns, (G-2)* (G-2) * 4 Ls. So 224 shapes for G=8. They wouldn’t normally intersect in practice but we can keep those.

I only need a low upper limit. E.g its at least 20 to 1. The alphabet size is 24. I am looking into the decoding of the dedication to Shake-speares sonnet’s. It’s quite astounding and I urge you to examine it. There is repeated triple validation of clues that are roughly of this form. I am now really curious what the chances are of any old code turning up thrice. I am bidding ~100 to 1 but it’s a total guess.