Get a number of rows with a cell

So, I need a formula that when i type in a cell x number, it gives me x rows.

For example I type 12 (months) and I get 12 rows with the range number 1-12.

Its for a project at college where I have to do a simulation and I need this in order to various things depending on the time the user wants to pay his loan.

Thanks

A1= x number

Try this in A2:

=IF(ROWS($A$2:A2)>$A$1,"",ROWS($A$2:A2))

Copy down.

It works, but could explain the formula?
what I did was =IF($M$4>B3;B3+1;""), where m4=the periods and b3 is 0 (manually inputed).