Changing Cell References inside INDIRECT function.

Howdy. So I'm fairly inexperienced with Excel, but have gotten myself into a project where something I want to do seems to have turned out to be something of a chore. I have multiple sheets, and I want to have a single summary sheet that pulls data from one of the other sheets based upon the contents of a specified cell on the summary sheet. Thanks to Google and some posts on this very site, I've figure out how to do that:

=INDIRECT($A$1&"!A1")

where the second "A1" is just an example. Now here comes the problem that brought me here: I need to 1. be able to drag-autofill the formula across many cells such that the second A1 is changing to refer to new, specified cells on the other sheet, and 2. have the cell references increment by more than 1 when filling down the column (specifically I need it to increment by 4).

This summary sheet it going to be pulling whether or not a radio has been signed out, and who has had that radio, during a particular day. It is the "who" part that involves the trouble, because each "who" is four rows down from the last. From my table:

C3: Who:
C4: Out:
C5: In:
C6: [BLANK ROW]
C7: Who:
C8: Out:
C9: In:

Therefore the cells (say) B2, B3, B4 need to pull from C3, C7, and C10.

So, any clues on how to get the second A1 to increment, and how to get it to increment by 4?