I can't figure out how to make the "A4" change to "A5" when I copy the
formula to the next row.

=SUM(INDIRECT("A4:A"&(B4-C4)))

My "B" column is probably redundant, it's just a counter for what row
I'm on. (It actually should be one more since I need a header row).
What I'm trying to do is Sum A4:A1 if C4 =4, (four rows), or if C4=1,
I want the sum of A4:A3.

Col A Col B(just a row counter) Col C Col D (sum I need)
2 1 1
4 2 0
6 3 2
9 4 1

I suppose column B can be omitted, and just use an offset from C ?

If the example above is legible, I would want the formula in D3 to be
the sum of A3:A1. (I need to offset A3 up two rows.)

Thanks, Tim