On the chromatic number of integral circulant graphs

Integral circulant graphs are a generalization of unitary Cayley graphs, recently studied by Klotz and Sander. The integral circulant graph Xn(D)Xn(D) has vertices 0,1,…,n−10,1,…,n−1, and two vertices aa and bb are adjacent iff gcd(x−y,n)∈Dgcd(x−y,n)∈D, where D⊆{d:d∣n,1≤d