A119708 Number of free hexagonal polygons of symmetry class D_(3h) and area n.

0, 0, 1, 1, 0, 1, 1, 0, 1, 4, 0, 3, 4, 0, 3, 12, 0, 6, 19, 0, 10, 41, 0, 16, 72, 0, 28, 149, 0, 50, 72, 0, 87, 557, 0

Offset: 1

Author

N. J. A. Sloane, Aug 27 2006

Keywords

• nonn
• more

References

• Markus Voege, Anthony J. Guttmann and Iwan Jensen, "On the number of benzenoid hydrocarbons", J. Chem. Inf. Comput. Sci., (2002), vol. 42, 456-466.

Crossrefs

Cf. A121212, A121211, A121210, A120991.