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A236581
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The number of tilings of a 7 X (4n) floor with 1 X 4 tetrominoes.
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1
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1, 5, 37, 269, 1949, 14121, 102313, 741305, 5371097, 38916077, 281964941, 2042966149, 14802232757, 107249008849, 777068573905, 5630220503025, 40793546383409, 295568073335893, 2141527121824885, 15516352499614333, 112423136012925517, 814557513519681785
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OFFSET
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0,2
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COMMENTS
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Tilings are counted irrespective of internal symmetry: Tilings that match each other after rotations and/or reflections are counted with their multiplicity.
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LINKS
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FORMULA
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G.f.: (1-x)^3/(-8*x+1+6*x^2-4*x^3+x^4).
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MAPLE
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g := (1-x)^3/(-8*x+1+6*x^2-4*x^3+x^4) ;
taylor(%, x=0, 30) ;
gfun[seriestolist](%) ;
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MATHEMATICA
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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