My column A is going to be a numbering column. The numbers need to go like so: OH2-00001x, OH2-00002x, OH2-00003x, OH2-00004x, etc. These are sequential so how can I get Excel to autofill these for me (so I don't have to manually input 15,000 of these!). The regular way of getting excel to autofill 1, 2, 3, 4 doesn't work with this. What kind of formula/macro/whatever do I need to get the results I want? Thanks!

Try filling in the first 3 or 4 rows. Then select those cells and drag the lower right corner down a few row. See if it fills in the sequence. If it does, then highlight all the cells and drag the corner down all 15000 rows.

If it doesn't work. Then just put the numbers in the rows and create the sequence. Then Concatenate that column with the text.

1) Put this formula in the first cell for the first number, do not edit the A1:

="OH2-"&TEXT(ROW(A1),"00000")&"x"

2) Copy that cell down as far as needed.

3) Highlight all the cells with the new formulas

4) Do a COPY, then PasteSpecial > Values