Rademacher's generalization of the reciprocity law Hans Rademacher found the following generalization of the reciprocity law for Dedekind sums: If a, b, and c are pairwise coprime positive integers, then Hence, the above triple sum vanishes if and only if (a, b, c) is a Markov triple, i.e. a solution of the Markov equation References Further reading Tom M. Apostol, Modular functions and Dirichlet Series in Number Theory (1990), Springer-Verlag, New York. (See chapter 3.) Matthias Beck and Sinai Robins, Dedekind sums: a discrete geometric viewpoint, (2005 or earlier) Hans Rademacher and Emil Grosswald, Dedekind Sums, Carus Math. Monographs, 1972. . Number theory Modular forms