A note on the power graph of a finite group

‎ Suppose Γ is a graph with V(Γ)={1‎,‎2,…‎,‎p} ‎and F={Γ1,…‎,‎Γp}is a family of‎ ‎graphs such that nj=|V(Γj)‎, ‎1≤j≤p‎. ‎Define‎ ‎Λ=Γ[Γ1,…‎,‎Γp] to be a graph with‎ ‎vertex set V(Λ)=⋃pj=1V(Γj) and edge set‎ ‎E(Λ)=(⋃pj=1E(Γj))∪(⋃ij∈‎‎E(Γ){uv;u∈V(Γi),v∈V(Γj)}). ‎The‎ ‎graph Λ is called the Γ-join of FF‎. ‎The power graph P(G) of a group G is the graph‎ ‎which has the group elements as vertex set and two elements are‎ ‎adjacent if one is a power of the other‎. ‎The aim of this paper is‎ ‎to prove that P(Zn)=Kϕ(n)+1‎+‎Δn[Kϕ(d1)‎,‎Kϕ(d2),…‎,‎Kϕ(dp)]‎, ‎where Δn is a graph with vertex and edge sets‎ V(Δn)={di | 1,n≠di|n‎,‎1≤i≤p} and‎ ‎E(Δn)={didj | di|dj‎,‎1≤i