On the addition of squares of units modulo n
Let Zn be the ring of residue classes modulo n , and let View the MathML source be the group of its units. 90 years ago, Brauer obtained a formula for the number of representations of c∈Zn as the sum of k units. Recently, Yang and Tang (2015) [6] gave a formula for the number of solutions of the equation View the MathML source with View the MathML source. In this paper, we generalize this result. We find an explicit formula for the number of solutions of the equation View the MathML source with View the MathML source.