Skipping every third row when referencing nearby column/cells

Hi all,
First post here, I see many questions get answered promptly so I decided to register. Here goes:

A1: 1
A2: 2
A3: 0
A4: 3
A5: 4
A6: 0
(& so on)

and I want to reference cells A1,2;4,5, and continuing 7,8, 10,11, etc
B1=A1
B2=A2
B3=A4
B4=A5
select+drag to automatically reference... it goofs up, misses one, and creates:
B5=A5 (not A7)
B6=A6 (not A8)
B7=A8 (not A10)
B8=A9 (not A11)

Now, I'm sure I could record a macro to do this & repeat it until I've completed the spreadsheet, but the case is not always just skipping every one row, sometimes it's 16 or 8 or... depends on the data table that I'm given. I am trying to make a template file so I can import new data and resolve a single column of the req'd values. Is there a neat way to do this?