  We express the number of lattice points inside certain simplices via
Dedekind-Rademacher sums. As an application, we prove a conjecture of
Kronheimer and Mrowka in the special case of Brieskorn spheres (with at most 4
singular fibers). This conjecture relates the Euler characteristic of the
Seiberg-Witten-Floer homology to the Casson invariant.
