A121210 Number of free hexagonal polygons of symmetry class C_(2h) and area n.

0, 0, 0, 1, 1, 7, 7, 35, 36, 169, 177, 807, 859, 3864, 4145, 18616, 20098, 90265, 97913, 440230, 479367, 2157946, 2357108, 10623852, 11634624, 52496803, 57618226, 260236031, 286164543, 1293603599, 1424824820, 6445885963, 7109939186, 32187437996, 35548330099

Offset: 1

Author

Parthasarathy Nambi, Aug 19 2006

Keywords

• nonn

Examples

			If n=10 then the number of free hexagonal polygons of symmetry class C_(2h) is 169 which is the tenth term in the sequence.
		

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_(2h) column.

Extensions

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

Corrected by R. J. Mathar, Oct 26 2006