Specific pattern needed, "Fill" won't recognize it

Hello,

My first post, but I did attempt to search for this question. I found many similar questions but nothing exact, so any help would be appreciated.

I am comparing two years' data, one on top of the other (Rows 1 and 2). For each cell in each row, I am referencing a cell from a different tab. This needs to be done with about 290 data items, so 580 rows.

When I attempt to copy the two rows down, it doesn't go in the correct order (skips a cell reference number). It looks like this:

Excel Forum Q.xlsx

If any one could help me out it would save me a lot of time considering each of the 580 rows has about 30 different column with each cell referencing various things.

Thanks,

M

c2=
=INDEX(Sheet2!A:A,CEILING(ROWS($A$1:A1)/2,1))
c3=
=INDEX(Sheet3!A:A,CEILING(ROWS($A$1:A1)/2,1))
select both fill down

well assuming the lookup rang doesn't change
so its =vlookup(sheet2!a1,some range,some column number,false)
and =vlookup(sheet3!a1,some range,some column number,false)
just replace the references with the index

vlookup(INDEX(Sheet2!A:A,CEILING(ROWS($A$1:A1)/2,1)),some range,some column number,false)
vlookup(INDEX(Sheet3!A:A,CEILING(ROWS($A$1:A1)/2,1)),some range,some column number,false)