Computing Eccentric Version of Second Zagreb Index of Polycyclic Aromatic Hydrocarbons (PAHk)

A Recently, Ghorbani et. al. introduced the eccentric versions of first and second Zagreb indices called third and fourth Zagreb indices defined as M 3 ( G ) = Σ uv ∊ E ( G ) ( ε ( u ) + ε ( ν )) and M 4 ( G ) = Σ ν ∊ V ( G ) ε ( ν ) 2 , respectively, where ε ( ν )is the eccentricity of the vertex ν . In this paper, we compute the closed formula for third Zagreb index of Polycyclic Aromatic Hydrocarbons (PAH k ).