I found this on another site:

"if you put A1 inside row(), then you can put the formula in
starting in any row and drag fill it down:

=CHAR((ROW(A1)-1)/26+65)&CHAR(MOD(ROW(A1)-1,26)+65)

(my own version of the formula)

as an example.


Regards,
Tom Ogilvy"

For me, this worked for AA, then for AB, I had to change the "A1"s to "A2"s, then I copied and Pasted-Special for the rest of the column, and it worked.

From: http://www.pcreview.co.uk/threads/ho...to-zz.1010611/