On a class number formula of Hurwitz

Authors :: William Duke
Árpád Tóth
Özlem Imamoglu
Source :: Journal of the European Mathematical Society, 23 (12)
Publication Year :: 2021
Publisher :: European Mathematical Society - EMS - Publishing House GmbH, 2021.
Abstract: In a little-known paper Hurwitz gave an infinite series representation of the class number for positive definite binary quadratic forms. In this paper we give a similar formula in the indefinite case. We also give a simple proof of Hurwitz's formula and indicate some extensions.<br />Journal of the European Mathematical Society, 23 (12)<br />ISSN:1435-9855<br />ISSN:1435-9863