microsoft excel – Google Spreadsheets: how to reference multiple rows every nth row?

I have a set of data in column A1 to A100. In column B, I would like to reference three rows from column A while skipping every other two rows, like this:

Column A
1
2
3
4
5
6
...
100

Column B
3
4
5
8
9
10
...

How do I do that? I can use the offset function to skip every nth row, but I can only make it display one row at a time, when I actually want three rows at a time.