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Search: id:A053090
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| A053090 |
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F^3-convex polyominoes on honeycomb lattice with given semi-perimeter. |
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+0
2
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| 1, 0, 3, 2, 6, 6, 12, 12, 21, 22, 33, 36, 50, 54, 72, 78, 99, 108, 133, 144, 174, 188, 222, 240, 279, 300, 345, 370, 420, 450, 506, 540, 603, 642, 711, 756, 832, 882, 966, 1022, 1113, 1176, 1275, 1344, 1452, 1528, 1644, 1728, 1853, 1944, 2079, 2178, 2322, 2430
(list; graph; listen)
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OFFSET
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3,3
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COMMENT
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Sequence is also given by the Poincare series of an ordinal Hodge algebra, or algebra with straightening law, that the three-strand braid group acts on. [From Stephen Humphries (steve(AT)math.byu.edu), Feb 06 2009]
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REFERENCES
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Fouad Ibn-Majdoub-Hassani. Combinatoire de polyominos et des tableaux decales oscillants . These de Doctorat. Laboratoire de Recherche en Informatique, Universite Paris-Sud XI, France.
Alain Denise, Christoph Durr and Fouad Ibn-Majdoub-Hassani. Enumeration et generation aleatoire de polyominos convexes en reseau hexagonal (French) [enumeration and random generation of convex polyominoes in the honeycomb lattice] . In Proceedings of 9th Conference on Formal Power Series and Algebraic Combinatorics, pages 222-234, 1997.
Stephen P. Humphries, Action of some braid groups on Hodge algebras. Comm. Algebra 26 (1998), no. 4, pages 1233-1242. See Proposition 3.4 on page 1241. [From Stephen Humphries (steve(AT)math.byu.edu), Feb 06 2009]
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FORMULA
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G.f.: x^3*[(1+x^3)/((1-x^2)^3*(1-x^3))]
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CROSSREFS
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Sequence in context: A062200 A114208 A014686 this_sequence A087237 A102004 A125764
Adjacent sequences: A053087 A053088 A053089 this_sequence A053091 A053092 A053093
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KEYWORD
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nonn
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AUTHOR
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Fouad Ibn Majdoub Hassani (Fouad.Hassani(AT)genset.fr), Feb 28 2000
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EXTENSIONS
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More terms from James A. Sellers (sellersj(AT)math.psu.edu), Mar 01 2000
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