A proper coloring of a graph $G$ is a function from the vertices of the graph to a set of colors such that any two adjacent vertices have different colors, and the chromatic number of $G$ is the minimum number of colors needed in a proper coloring of a graph. In this paper, we will find the chromatic number of the Harary graphs, which are the circulant graphs in some cases.
"Chromatic number of Harary graphs." Tbilisi Math. J. 9 (1) 271 - 278, June 2016. https://doi.org/10.1515/tmj-2016-0013