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A126765
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a(n) = number of L-convex polyominoes inscribed in an (n+1) X (n+1) box.
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2
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1, 5, 42, 402, 4070, 42510, 452900, 4891988, 53376966, 586921790, 6493225772, 72192371100, 805935279708, 9028253155628, 101433497725320, 1142504966609512, 12897113121607750, 145870996300613406, 1652690392388658012, 18753389068268792780, 213091273336786301940
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| See A126764 for definition of L-convex.
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REFERENCES
| G. Castiglione, A. Frosini, E. Munarini, A. Restivo and S. Rinaldi, Combinatorial aspects of L-convex polyominoes, to appear in European Journal of Combinatorics, 2007.
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FORMULA
| G.f.: (1/2) * sqrt( (2+5*x-2*x^2+(2-x)*sqrt(1-12*x+4*x^2) )/ (1-12*x+4*x^2) ).
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MATHEMATICA
| CoefficientList[Series[(1/2)Sqrt[(2+5x-2x^2+(2-x)Sqrt[1-12x+4x^2])/ (1-12x+4x^2)], {x, 0, 20}], x] (* From Harvey P. Dale, June 14 2011 *)
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CROSSREFS
| Cf. A000105, A126764.
Sequence in context: A025173 A062021 A082145 * A024492 A005789 A151334
Adjacent sequences: A126762 A126763 A126764 * A126766 A126767 A126768
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Feb 23 2007
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