I shall refer to the number of terms on the left side of the equation as $m$. Suppose that all numbers in the equation are positive integers. I am wondering if anything is known about for which values of $m$ and $n$ this equation has infinitely many or no solutions. I know that the case for $m=2$ is solved (this reduces to Fermat's Last Theorem when $m=2$) and that $m>2$ are trivial, but is anything known for higher $m$? If so, is there a type of "generalized Fermat's Last Theorem" to encompass these cases with $m>2$?