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A121211 Number of free hexagonal polygons of symmetry class D_(2h) and area n. 1
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 (list; graph; refs; listen; history; text; internal format)
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.

LINKS

Table of n, a(n) for n=1..35.

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: A116450 A054172 A236971 * A316585 A146157 A238363

Adjacent sequences:  A121208 A121209 A121210 * A121212 A121213 A121214

KEYWORD

nonn

AUTHOR

Parthasarathy Nambi, Aug 19 2006

STATUS

approved

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Last modified December 12 18:24 EST 2018. Contains 318081 sequences. (Running on oeis4.)