How to autofill a column with numbers and maintain it when adding or removing rows?

So far I discovered two ways to autofill a column with increasing numbers:

1. Type "1" into one cell, "2" into the one below, select both, then use the yellow dot to drag it down - it will do the rest.

2. Create a basic formula such as "A2 + 1" and also drag it.

However, in both cases it will only work if I manually keep doing this for every newly added row at the bottom. Now, this alone wouldn't be that big of an issue if it wasn't for the fact that I'm working with a table where rows may be added in between other rows in the future.

That said, could someone please tell me how do I create a column with numbers that will increase automatically? I mean - if I add a new row between row 56 and 57, I want the new row to have a "57" in it and the "old 57" would now be "58" and so on. I don't want to drag the whole column which may have hundreds if not over a thousand rows.