Regular Expression Notepad increment numbers in every line

It's not possible to accomplish this with a regular expression, as you will need to have a counter and make arithmetic operations (such as incrementing by one).

If you want to do this with notepad++ you can do it in the following way.

First you can write all the 700 lines with template text (you can use a Macro or use the Edit -> Column Editor). Once you have written it, put the cursor on the place you want the number, click Shift+Alt and select all the lines: