The Balaban index J is a graph index defined for a graph on n nodes, m edges, and c connected components by J = m/(γ + 1) sum_((i, j) element E(G)) (D_i D_j)^(-1/2), where γ = m - n + c is the circuit rank of the graph, E(G) is the edge set, and D_i is the sum of all entries in the ith row (or column) of the graph distance matrix. Unless otherwise stated, hydrogen atoms are usually ignored in the computation of such indices as organic chemists usually do when they write a benzene ring as a hexagon.