Sum CAGR without final value?

Let's assume there are 4 periods, you know the first period's # and what the sum of the total compounded periods should be, so what formula would you use to find the rest of the periods values? For example, first period is 400, and the sum of the 4 periods is 3,847. What number is in period 2,3,4? I would use the cagr formula if I knew the final value, but wondering if you all have come across this before or have any ideas? Any help is much appreciated.

Edit: The sum of the four periods would be the input. - I am basically reversing a yearly input into a quarterly basis. I have the 1st quarter numbers for historicals and can finagle future 1st quarters, but feel free to disregard info of 1st quarter # if that helps. I can't do a constant growth rate across the board since inputs will need to be able to adjusted on a yearly basis.

Edit 2: Reworded: If I have 1) sum value of 3,845   and    2) assume a quarterly growth rate of 7% (arbitrary), how do I determine values of each quarter? Hardcoded answers:

Q1 - 866

Q2 - 926.6

Q3 - 991.5

Q4 1060.9

Inputs : sum=3,845 and 7% Quarterly CAGR

Want to find a function or way to do this so that the input can be updated and quarters are auto-adjusted

FINAL: I am stupid. If anyone is revisiting this, don't try to overcomplicate things in your model.