Using x=f-1 as the basis to chain records together enables large jumps in both (e,1) and (-f,1).
Attached pics are for c145 and c551 and show only the (e,n,t) values in their x=f-1 sequences.
For c145, the starting (1,1,12) record represents the x=f-1 move from (1,61,6) where f=24. Records for subsequent moves upwards are created by e,n,x where x=f-1, using f from the current record.
For c551, the starting (-25,1,37) record represents the x=f move from (22,253,12) where f=25. Note the use of x=f when moving from the e column to -f column. Subsequent moves up then follow the x=f-1 formula from the current record.
When moving in reverse, both columns behave similarly.
The previous d value can be calculated as:
previous_f = x + 1;
previous_d = ( previous_f + e - 1 ) / 2;
And then records can be created using the e,n,d values.