Excel auto fill a column with increment

Use the Goto command to go to row 20,000 and enter some text in the column that you want to fill.

Go to the top, enter the first 2 numbers.

Select the two cells. Use Ctrl-Shift-Down Arrow to select all cells down to row 20,000. Click Home ribbon > Fill drop-down > Series > OK

1. Fill in the value for your first cell.
2. RIGHT click the fill handle, pull down and then back up.
3. In the menu box that pops up click "Series".
4. In the message box be sure to check "Columns".
5. Assuming that the "Step value" is "1" enter 20000 in the "Stop value:" window.
6. Click "OK".

Inspired by this answer,

• Click in the Name Box (to the left of the Formula Bar) and type a range that covers the cells that you want to fill.  For example, if you are in column Q and you have a header row, type Q2:Q20001.  Type Enter.  The cells will be selected.
• Click in the Formula Bar and type ROW()-1.  (Replace the 1 with the number of header rows you are skipping.)  Type Ctrl+Enter.  This will fill the cells with the (apparent) values 1 through 20000.

If this is good enough for you, quit.  Otherwise,

• Copy (e.g., by typing Ctrl+C).
• Click on the Paste menu, and select “Paste Values”.