A030520 Number of polyhexes of class PF2 with C_{2n} symmetry.

0, 1, 5, 20, 82, 335, 1402, 5949, 25652, 111963, 494157, 2201270, 9886034, 44712737, 203489627, 931191850, 4282171470, 19778577235, 91715812335, 426824400684, 1992828161414, 9332192498397, 43821128181652, 206288470970025, 973361629499032, 4602638827207605

Offset: 2

Author

N. J. A. Sloane

Keywords

• nonn

Comments

See reference for precise definition.

Links

• S. J. Cyvin, Zhang Fuji, B. N. Cyvin, Guo Xiaofeng, and J. Brunvoll, Enumeration and classification of benzenoid systems. 32. Normal perifusenes with two internal vertices, J. Chem. Inform. Comput. Sci., 32 (1992), 532-540.

Crossrefs

Cf. A026106, A026118, A026298, A030519, A030520, A030525, A030529, A030532, A030534.

Extensions

Title improved, a(2)=0 inserted, and more terms from Sean A. Irvine, Apr 02 2020