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A121211
Number of free hexagonal polygons of symmetry class D_(2h) and area n.
2
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
1,4
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.
EXAMPLE
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.
CROSSREFS
Sequence in context: A054172 A236971 A373446 * A316585 A369765 A146157
KEYWORD
nonn
AUTHOR
Parthasarathy Nambi, Aug 19 2006
STATUS
approved