Yup, I agree.
Hmm. Here's where my mind is at.
I'm thinking the next step is to find SQRT d and any remainders. Somehow they help unlock the next step.
For the END:
We solved the E by moving from e to negative f and finding the matching records
N is finding the an, bn, a(n-1), and b(n-1) pattern
D is using sqrt d to unlock how to move from the na transform to the correct records for either a(n-1), b(n-1), etc.
If we can move to the correct record, we got this solved.
Here's the idea I'm working on, just putting this out there, needs more verification:
c287
d=16, sqrt d=4
I think maybe we move from our (-2,1) -f na transform, which is t=8 a=127,
to t[8+4] = t[12] = 287
Whaddya know, it's our b(n-1) value.
Which means in (31,1) we go to t[8+4+1]=328
328-287= 41 = b
287/41 = 7= a
solved.
(for this example, lol! Needs more testing)