Originally Posted by

**colerelm1** I have a series that goes by the form of:

1 + a + a^2 + a^3 +...+ a^n

where n is the number of terms in the series (not including the 1 at the beginning). So, for example, the series with 4 terms would take the form

1+ a + a^2 + a^3 + a^4

Is there a way to represent this in a non-geometric series type of way? More specifically, if I wanted a=3 and n=4, then the series looks like:

1 + 3 + 3^2 + 3^3 + 3^4 = 118

Is there a way to get 118 without a series representation and only knowing a=3 n=4?