Is there a way to express this equation where you have an integer $x$ and an integer $n$ and you do:

$$
x^n + x^{n-1} + x^{n-2} + ... + x^{n-n}
$$

Is there a name for this type of equation and how can I write it more succinctly? I haven't done math in so long and don't even know how to search for this