A FORMULA PERIODIC TABLE FOR BENZENOID HYDROCARBONS AND THE AUFBAU AND EXCISED INTERNAL STRUCTURE CONCEPTS IN BENZENOID ENUMERATIONS

The genesis of the aufbau and excised internal structure concepts is traced. These concepts were pivotal to the first published enumerations of the strictly peri-condensed, non-Kekulean, and essentially strain-free total resonant sextet benzenoid groups. A periodic table set is defined as a partially ordered set forming a two-dimensional array which complies with the triad principle where a central element has a metric property that is the arithmetic mean of two adjacent surrounding member elements.