Do you mean that you want A to Z on rows 1 to 26, then AA, AB, AC etc
up to ZZ in row 702, then AAA, AAB, AAC and so on, and eventually
AAAA, AAAB, AAAC and so forth until you run out of rows?
Or, do you mean that you want AAAA on row 1, which will then become
AAAB, AAAC, AAAD etc on subsequent rows?
Do you want upper case, as shown, or lower case?
Please advise further.
Pete