Results of Hurwitz type for three squares.
If \(n\) is a natural number, let \(r_3(n)\) be the number of representations of \(n\) as a sum of three squares. Using theta functions, the authors obtain generating functions for \(r_3(an+ b)\) in 103 separate choices of \(a\) and \(b\). In addition, they obtain 33 theta function identities.
scientific article; zbMATH DE number 2032850