The automorphism group of the Andrasfai graph

Abstract

c © 2022 the author. This is an open access article under the CC BY (International 4.0) license (www.creativecommons.org/licenses/by/4.0/). Abstract For n = 3k−1, denote by Zn the additive group of integers modulo n, where k is an integer greater than 1. Let C be the subset of Zn consisting of the elements congruent to 1 modulo 3. The Andrásfai graph And(k) is the Cayley graph Cay(Zn;C). In this note, it is shown that the automorphism group of the graph And(k) is isomorphic to the dihedral group of order 2n.