Identify the sequence type

Denote $a\ne 1$ as a positive constant.

Let $x_1, x_2, \ldots , x_n$ form an arithmetic progression .

If we apply these numbers under the transformation $y = a^x$ , we will obtain the numbers $y_1, y_2, \ldots , y_n$ that follows a/an $\text{\_\_\_\_\_\_\_\_\_\_}.$