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A001207
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Number of fixed hexagonal polyominoes with n cells.
(Formerly M2897 N1162)
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10
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1, 3, 11, 44, 186, 814, 3652, 16689, 77359, 362671, 1716033, 8182213, 39267086, 189492795, 918837374, 4474080844, 21866153748, 107217298977, 527266673134, 2599804551168, 12849503756579, 63646233127758, 315876691291677, 1570540515980274, 7821755377244303, 39014584984477092, 194880246951838595, 974725768600891269, 4881251640514912341, 24472502362094874818, 122826412768568196148, 617080993446201431307, 3103152024451536273288, 15618892303340118758816, 78679501136505611375745
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| The Voege-Guttmann paper extends the series to n=35. - Markus Voege (markus.voege(AT)inria.fr), Mar 25 2004
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REFERENCES
| W. F. Lunnon, Counting hexagonal and triangular polyominoes, pp. 87-100 of R. C. Read, editor, Graph Theory and Computing. Academic Press, NY, 1972.
Mertens, Stephan; Lautenbacher, Markus E.; Counting lattice animals: a parallel attack. J. Statist. Phys. 66 (1992), no. 1-2, 669-678.
D. H. Redelmeier, personal communication.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
Markus Voege and Anthony J. Guttmann, On the number of hexagonal polyominoes, Theoretical Computer Sciences, 307(2) (2003), 433-453.
A. J. Guttmann, ed., Polygons, Polyominoes and Polycubes, Springer, 2009, p. 477. (Table 16.9 has 46 terms of this sequence.) [From Robert A. Russell (russell(AT)post.harvard.edu), Nov 05 2010]
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LINKS
| Moa Apagodu, Counting hexagonal lattice animals.
Markus Voege and Anthony J. Guttmann, On the number of hexagonal polyominoes
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CROSSREFS
| Sequence in context: A167013 A121220 A068091 * A026887 A151106 A151107
Adjacent sequences: A001204 A001205 A001206 * A001208 A001209 A001210
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KEYWORD
| nonn,nice
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| 3 more terms and reference from Achim Flammenkamp (achim(AT)uni-bielefeld.de) Feb 15 1999.
More terms from Markus Voege (markus.voege(AT)inria.fr), Mar 25 2004
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