In[]:=
n=20;(*Howmanyverticesdoyouwant?*)​​k=1;(*Towhatpowerdoyouwishtoraiseyourfunction?*)​​​​(*Iwouldn'trecommendeditingbelowthiscommentunlessyouknowwhatyou'redoing*)​​​​GraphPlot[Table[Rule@@{i+1,Mod[i+k,n]+1},{i,0,n-1}],VertexLabelsPlaced[Automatic,Center],VertexSize.5,DirectedEdgesTrue]
Out[]=