Create a 60 month * 6% increase series, starting with an initial value of 1
The result is about 32.99
Now select the last cell - the one with the result of 32.99
Use the Goal Seek function:
This will assume that the cell selected is the one to be set to the goal. Enter 397224 as the goal and select the 'cell to change' to be the first one in your series, i.e., the cell you entered 1 in.
Click OK, and the first cell in your series will be successively changed until the result of your series is 397224.
I don't have Excel 2007 on this PC, so I can't walk you through finding the goal seek function from the Ribbon.