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Search: id:A006027
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| A006027 |
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Number of directed column-convex polyominoes with perimeter 2n+2.
(Formerly M1647)
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+0
4
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| 1, 1, 2, 6, 20, 71, 263, 1005, 3933, 15684, 63505, 260390, 1079019, 4511700, 19011521, 80653480, 344193353, 1476589475, 6364258163, 27545933212, 119676949397, 521739175908, 2281673067934, 10006784399183
(list; graph; listen)
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OFFSET
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1,3
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REFERENCES
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M.-P. Delest, Utilisation des Langages Alg\'{e}briques et du Calcul Formel Pour le Codage et l'Enumeration des Polyominos. Ph.D. Dissertation, Universit\'{e} Bordeaux I, May 1987.
Delest, M.-P., Generating functions for column-convex polyominoes. J. Combin. Theory Ser. A 48 (1988), no. 1, 12-31.
M.-P. Delest and S. Dulucq, Enumeration of directed column-convex animals with given perimeter and area, Croat. Chem. Acta. 66 (1993), 59-80.
E. Duchi and S. Rinaldi, An object grammar for column-convex polyominoes, Annals of Combinatorics, 8 (2004), 27-36.
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FORMULA
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G.f. A(x) = a(1)x^2 + a(2)x^3 + a(3)x^4 + ... satisfies the functional equation A^3 + 2(x-1)A^2 + (2x-1)(x-1)A + (x^2)(x-1) = 0. - D. G. Rogers, May 22 2005
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CROSSREFS
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Cf. A005435.
Sequence in context: A129777 A108600 A128729 this_sequence A049124 A049141 A049129
Adjacent sequences: A006024 A006025 A006026 this_sequence A006028 A006029 A006030
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KEYWORD
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nonn
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AUTHOR
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Simon Plouffe (plouffe(AT)math.uqam.ca)
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EXTENSIONS
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More terms from Douglas Rogers and Emanuele Munarini, May 15 2005
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