Computing fifth geometric-arithmetic index for nanostar dendrimers

The geometric-arithmetic index is a topological index was defined as GA(G)=∑uv2(dudv)1/2/(du+dv), in which degree of vertex u denoted by dG(u ). Now we define a new version of GA index as GA5(G)=∑uv2(δuδv)1/2/(δu+δv) ,  where δu=∑uvdv. The goal of this paper is to further the study of the GA5 index.