skipping lines when auto-filling equations

Alright, this question has been bothering me for some time now. I want to autofill an equation to save me some time, but it's 'smart' autofilling isn't quite smart enough for me. Here's an example of what I am trying to accomplish:

I have 4 cells of information, aligned vertically as follows (assuming the first is A1):

1
2
3
4

and i have an equation that says '=A1' in an adjacent cell
when I autifill the cells below the formula '=A1' I would like it to skip every other cell, so the formulas should result as follows:
=A1
=A3
=A5
=A7
and so on.
Is this possible?
The reason being is that I have a long equation that is supposed to take information from a different excel file that I download from the internet from time to time that I want every even row's information in the left column and every odd row's information in the column adjacent to it, resulting in something like this:

=A1 =A2
=A3 =A4
=A5 =A6
and so on

and the equation is pretty long so I don't want to have to re type it over and over or change every single cell manually.
Attached is another example of what I'm trying to do.
Thanks for any advice!example of auto fill problem.xlsx