Advanced cell reference
 

Hello,

Let me explain my question with an example.
In cell A1, I have the value 2.
In cell A7 the value 5.
In cell A12 the value 9.
So there is always an interval of 5 cells for the data I want.

How can I make excel do this in a formula?
For example
if I make the next formulas
=A1
=A7
=A12

I would like when dragging it down that the next cells have
=A17
=A22
=A27

And so on. How can I do this?
Thank you very much for your help.

Kind regards,
Filip