Some structural relationships between acenes and cyclacenes both H\\"{u}ckel- and Mobius-type and within the same class of compounds were demonstrated by the recursive analysis of their Ep and Ip values or the first differences thereof. It was found that the first differences of Ep and Ip tend to have certain limit values as the number of benzenoid rings increases in each class of compounds studied.

Some structural relationships between acenes and cyclacenes both H\\"{u}ckel- and Mobius-type and within the same class of compounds were demonstrated by the recursive analysis of their Ep and Ip values or the first differences thereof. It was found that the first differences of Ep and Ip tend to have certain limit values as the number of benzenoid rings increases in each class of compounds studied.