I need to calculate an NPV that could start in any given year and end in a
later given year to provide a stream of income.

For example - I have a 30 years for this case. Income will start in year 16
and end in year 30. For a level $100,000 of income in the income period at
10% at beginning of year, I get $836,668.75. If it is only 10 years, the NPV
is $675,902.38.

How can I - by formula - adjust the start and end addresses for the NPV?

I've tried Address, Indirect, and a few others but I'm doing something wrong.

Is there a way to make this work by formula?