Generalized Shioda-Inose Structures on K3 Surfaces

We examine the finite group actions on K3 and Abelian surfaces giving the same orbit space after desingularization. We show that when the group is not Z_2, then the Picard number of the K3 surface must be 19 or 20, and that in the latter case the Abelian surface is uniquely determined by the K3 surface.