Overpartitions and class numbers of binary quadratic forms

Kathrin Bringmann, Jeremy Lovejoy

Published 2007-12-04Version 1

We show that the Zagier-Eisenstein series shares its non-holomorphic part with certain weak Maass forms whose holomorphic parts are generating functions for overpartition rank differences. This has a number of consequences, including exact formulas, asymptotics, and congruences for the rank differences as well as $q$-series identities of the mock theta type.