0,3

B. N. Cyvin et al., A class of polygonal systems representing polycyclic conjugated hydrocarbons ..., Monat. f. Chemie, 125 (1994), 1327-1337 (see Table 1).

S. J. Cyvin et al., Enumeration and classification of certain polygonal systems... : annelated catafusenes, J. Chem. Inform. Comput. Sci., 34 (1994), 1174-1180.

See A044046 for g.f. and other formulae.

Equals twice A044046.

Sequence in context: A003087 A109243 A108327 this_sequence A092199 A108485 A018940

Adjacent sequences: A121068 A121069 A121070 this_sequence A121072 A121073 A121074

nonn

N. J. A. Sloane (njas(AT)research.att.com).