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Search: id:A082398
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| A082398 |
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Number of directed, diagonally convex polyominoes with n cells. |
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+0
1
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| 1, 0, 3, 10, 33, 106, 331, 1009, 3017, 8884, 25841, 74416, 212533, 602785, 1699503, 4767166, 13312641, 37031254, 102651967, 283676689, 781763381, 2149017256, 5894114513, 16132400860, 44071485673, 120188174401, 327242994651
(list; graph; listen)
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OFFSET
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1,3
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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.
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FORMULA
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G.f.: (x*(1-4*x+6*x^2-3*x^3+x^4))/((1-x)*(1-3*x+x^2)^2)
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MATHEMATICA
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Join[{1, 0}, Take[CoefficientList[Series[(q*(1 - 4*q + 6*q^2 - 3*q^3 + q^4))/((1 - q)*(1 - 3*q + q^2)^2), {q, 0, 27}], q], -26]]
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CROSSREFS
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Sequence in context: A096483 A093043 A061566 this_sequence A053156 A120897 A077825
Adjacent sequences: A082395 A082396 A082397 this_sequence A082399 A082400 A082401
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KEYWORD
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nonn,easy
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AUTHOR
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Fouad IBN MAJDOUB HASSANI (fouad.ibnmajdoubhassani(AT)wanadoo.fr), Apr 14 2003
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Apr 15 2003
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