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A121220 Number of fixed hexagonal polygons (or benzenoids) with n cells. 1
1, 3, 11, 44, 186, 813, 3640, 16590, 76663, 358195, 1688784, 8022273, 38351973, 184353219, 890371070, 4318095442, 21018564402, 102642526470, 502709028125, 2468566918644, 12150769362815, 59937663454017 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

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 2 under the B_h column on page 462.

LINKS

N. J. A. Sloane, Table of n, a(n) for n = 1..46 [from Jensen link]

I. Jensen, First 46 terms

Iwan Jensen, A parallel algorithm for the enumeration of benzenoid hydrocarbons, arXiv:0808.0963v1 [cond-mat.stat-mech].

FORMULA

See equation 11 on page 463 of the paper by Markus Voege, Anthony J. Guttmann and Iwan Jensen for an asymptotic form for a(n).

CROSSREFS

Cf. A018190.

Sequence in context: A061706 A167012 A167013 * A068091 A001207 A026887

Adjacent sequences:  A121217 A121218 A121219 * A121221 A121222 A121223

KEYWORD

nonn

AUTHOR

Parthasarathy Nambi, Aug 20 2006

EXTENSIONS

More terms from N. J. A. Sloane, Aug 25 2006

STATUS

approved

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Last modified March 30 15:48 EDT 2017. Contains 284302 sequences.