

A121210


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


1



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
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OFFSET

1,6


REFERENCES

Markus Voege, Anthony J. Guttmann and Iwan Jensen, "On the number of benzenoid hydrocarbons", J. Chem. Inf. Comput. Sci., (2002), vol. 42, 456466. See Table 3 under the C_(2h) 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_(2h) is 169 which is the tenth term in the sequence.


CROSSREFS

Sequence in context: A286830 A286862 A290683 * A241866 A243123 A154702
Adjacent sequences: A121207 A121208 A121209 * A121211 A121212 A121213


KEYWORD

nonn


AUTHOR

Parthasarathy Nambi, Aug 19 2006


EXTENSIONS

More terms from N. J. A. Sloane, Aug 27 2006
Corrected by R. J. Mathar, Oct 26 2006


STATUS

approved



