Abstract. In this paper, we show that N (f ) = |L(f )| for any continuous selfmap f : M → M on an infra-nilmanifold M of which the holonomy group is 2-perfect (i.e. having no index two subgroup). Conversely, for any finite group F that is not 2-perfect, we show there exists at least one infra-nilmanifold M with holonomy group F and a continuous selfmap f : M → M such that N (f ) = |L(f )|.