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

The overall set of acyclic hydrocarbons CnH2m with classical valence structures 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 → ∞ 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-exponentially, as a power of n.

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