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The Narumi-Katayama topological indes S of a hydrocarbon is the product of vertex degrees of the respective molecular graph. If PH is a phenylene and HS is its hexagonal squeeze, then the respective Narumi-Katayama indices are related as S(PH) = 9h1 S(HS), where h is the number of hexagons of PH and HS, or as S(PH) = S(HS)b , where a = 0.078 and b = 1.613.

Let G be a molecular graph possessing m0(G) edges. let m1(G) be the number of edges of the line graph L(G) of G, known as the Bertz index. Let m2(G) be the number of edges of the line graph of L(G), etc. We examine the applicability of the sequence mi(G), i = 0, 1, 2, ..., for predicting physicochemical properties of alkanes. Some earlier obtained results are extended and amended.