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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 (list; graph; refs; listen; history; text; internal format)
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, 456-466. 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

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Last modified December 13 01:33 EST 2017. Contains 295954 sequences.