Hello Lads! Found something important.
I followed VQC's clues and found an, ab, a(n-1), and b(n-1) in our -f and e cells.
Use my handwritten notes to look for an, ab, a(n-1), b(n-1)
they are t+n and t+n-1 elements apart in the record, just like he said.
Can Anons verify please?