hmmmm.....the way I was taught TVM is (1+R)^(1/n) gives you an annualized rate of growth that covers all years and no final adjustment is needed. As a simple example:
Going Forward: $1 PV, n=30 Years, i=10%. FV calculated to = $17.4494
Go Backward: $17.4494 FV, n=30 Years, i=10%, PV...