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A053091
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F^3-convex polyominoes on the honeycomb lattice by number of cells.
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0
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1, 3, 5, 6, 9, 11, 10, 15, 18, 14, 21, 23, 18, 30, 29, 21, 33, 35, 31, 39
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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REFERENCES
| 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.
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FORMULA
| G.f.: sum_{n >= 0}sum{d|n}b_i^2*(1+x^d)*x^(n-d), where b_0=0 and b_i=x^binomial(i+1, 2)*sum_{k=1}^{i}x^(-binomial(i+1, 2)) for i >= 1
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CROSSREFS
| Sequence in context: A081175 A094598 A122194 * A047271 A047445 A205534
Adjacent sequences: A053088 A053089 A053090 * A053092 A053093 A053094
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KEYWORD
| nonn
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AUTHOR
| Fouad Ibn Majdoub Hassani (Fouad.Hassani(AT)genset.fr), Feb 28 2000
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