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Search: id:A005768
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| A005768 |
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Number of convex polygons of length 2n on square lattice whose left-most bottom vertex is strictly to the left of the right-most top vertex.
(Formerly M1776)
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+0
4
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| 1, 2, 7, 27, 110, 460, 1948, 8296, 35400, 151056, 643892, 2740216, 11639416, 49340080, 208727176, 881212272, 3713043152, 15615663008, 65555425780
(list; graph; listen)
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OFFSET
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2,2
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REFERENCES
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M.-P. Delest and G. Viennot, Algebraic languages and polyominoes enumeration, Theoretical Computer Sci., 34 (1984), 169-206.
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FORMULA
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G.f. x^2*(1-8*x+21*x^2-19*x^3+4*x^4)/((1-2*x^(1/2))^2*(1+2*x^(1/2))^2*(1-2*x)) - 2*x^4*(1-4*x)^(-3/2) - Markus Voege (voege(AT)blagny.inria.fr), Nov 28 2003
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CROSSREFS
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A005436(n) = a(n) + A005769(n) + A005770(n)
Sequence in context: A136412 A026726 A026759 this_sequence A106225 A127897 A011965
Adjacent sequences: A005765 A005766 A005767 this_sequence A005769 A005770 A005771
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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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Better description from Markus Voege (voege(AT)blagny.inria.fr), Nov 28 2003
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