The crossing number of C(3k+1;{1,k})C(3k+1;{1,k})

In this paper, we study the crossing number of the circulant graph C(3k+1;{1,k})C(3k+1;{1,k}) and prove that cr(C(3k+1;{1,k}))=k+1cr(C(3k+1;{1,k}))=k+1 for k⩾3k⩾3.