There is a very clear pattern that each consecutive result will be missing the next product in its denominator. Is there a simpler closed form representation of this result? Maybe a combinatorics formula with factorials or harmonic numbers?
If you are having trouble with understanding this, look more closely at the location of the $i$ index to notice it is in the sub-script, not the super-script. If such an index was in the super-script, and you assumed $x$ was a real variable, then and only then could each term be assumed as a mononomial resulting in an overall polynomial in the sum, followed by reciprocals of mononomials on the right-hand side.