Formula periodic table for the isomer classes of acyclic hydrocarbons - Enumerative and asymptotic characteristics

The overall set of acyclic hydrocarbons CnH2m with classical valence struct ures is considered, the structural isomers are enumerated, and the results displayed in the form of a >>periodic table<< with the C atom count n and H atom half-count m respectively identifying rows and columns. Asymptotic n --> infinity behaviors of these enumerations are developed, first for fixed degree u = n+1-m of unsaturation and second for fixed number 2m of H-atoms . The first-set isomer classes increase in size exponentially fast with n, whereas with the second set, the isomer-class sizes increase sub-exponentia lly, as a power of n.