A121211 Number of free hexagonal polygons of symmetry class D_(2h) and area n.

0, 1, 1, 2, 2, 3, 3, 6, 7, 11, 14, 21, 23, 41, 50, 80, 94, 156, 189, 310, 365, 615, 748, 1237, 1459, 2488, 3023, 5059, 5994, 10296, 12511, 21149, 25100, 43451, 52870

Offset: 1

Author

Parthasarathy Nambi, Aug 19 2006

Keywords

• nonn

Examples

			If n=10 then the number of free hexagonal polygons of symmetry class D_(2h) is 11 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 D_(2h) column.