A120991 Number of free hexagonal polygons of symmetry class C_(2c) and area n.

0, 0, 1, 1, 9, 12, 39, 61, 178, 274, 796, 1251, 3578, 5692, 16290, 26069, 74980, 120676, 348564, 563503, 1635175, 2652445, 7729807, 12574028, 36784467, 59975232, 176063801, 287613473, 846967739, 1385815492, 4092516853, 6705360813, 19852731854, 32565589836, 96642900684

Offset

1,5

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. See Table 3 under the C_(2c) column.

Links

Table of n, a(n) for n=1..35.

Example

If n=10 then the number of free hexagonal polygons of symmetry class C_(2c) is 274 which is the tenth term in the sequence.

Crossrefs

Sequence in context: A216297 A024312 A024877 * A253088 A341208 A328120

Adjacent sequences: A120988 A120989 A120990 * A120992 A120993 A120994

Keyword

nonn

Author

Parthasarathy Nambi, Aug 19 2006

Extensions

More terms from N. J. A. Sloane, Aug 27 2006

Status

approved