For rows, enter this in the first row and drag down. (Add numbers to ROW() as in
ROW() + 2 if you want to start in say Row 3)
For columns, enter this in the first column and drag right. (Add numbers to
COLUMN as in COLUMN() + 2 if you want to start in
say Column C)
Note both formulas will automatically adjust if your list does not start in the
first row (first formula) or column (second formula) accordingly.