Well, yes, but that's something of an anachronism. Technically, a "Miller index" of h,k,l can only be a triplet of prime numbers (Miller, W. (1839). A treatise on crystallography. For J. & JJ Deighton.). This is because Miller was trying to explain crystal facets, and facets don't have "harmonics". This might be why Bragg decided to put an "n" in there. But it seems that fairly rapidly after people starting diffracting x-rays off of crystals, the "Miller Index" became generalized to h,k,l as integers, and we never looked back.