The minimum aberration criterion is commonly used for selecting good fractional factorial designs. In this paper we obtain minimum aberration 2n-k designs for k = 3,4 and any n. For k > 4 analogous results are not available for general n since the resolution criterion is not periodic for general n and k > 4. However, it can be shown that for any fixed k, both the resolution criterion and the minimum aberration criterion have a periodicity property in n for s(n-k) designs with large n. Furthermore, the optimal-moments criterion is periodic for any n and k.