EN
Let r,m be positive integers with r > 1, m even, and A,B be integers satisfying $A + B√(-1) = (m + √(-1))^{r}$. We prove that the Diophantine equation $|A|^x + |B|^y = (m² + 1)^z$ has no positive integer solutions in (x,y,z) other than (x,y,z) = (2,2,r), whenever $r > 10^{74}$ or $m > 10^{34}$. Our result is an explicit refinement of a theorem due to F. Luca.