%N Polycyclic aromatic hydrocarbons (for precise definition see He and He, 1986).
%H Wenchen He and Wenjie He, <a href="https://doi.org/10.1016/S0040-4020(01)82078-0">Generation and enumeration of planar polycyclic aromatic hydrocarbons</a>, Tetrahedron 42.19 (1986): 5291-5299. See Table 1.
%Y Cf. A003104, A323923-A323929.
%Y A018190 is a very similar sequence with (as He and He remark) a slightly different definition.
%A _N. J. A. Sloane_, Feb 09 2019