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A068924
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Number of ways to tile a 5 X 2n room with 1x2 Tatami mats. At most 3 Tatami mats may meet at a point.
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2
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6, 3, 2, 2, 4, 4, 6, 8, 10, 14, 18, 24, 32, 42, 56, 74, 98, 130, 172, 228, 302, 400, 530, 702, 930, 1232, 1632, 2162, 2864, 3794, 5026, 6658, 8820, 11684, 15478, 20504, 27162, 35982, 47666, 63144, 83648, 110810, 146792, 194458, 257602, 341250
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| For n >= 3, a(n) = 2*A000931(n+3).
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REFERENCES
| F. Ruskey and J. Woodcock, Counting Fixed-Height Tatami Tilings, Electronic Journal of Combinatorics, Paper R126 (2009) 20 pages. [From Frank Ruskey (ruskey(AT)cs.uvic.ca), Sep 26 2010]
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FORMULA
| For n >= 6, a(n) = a(n-2) + a(n-3).
G.f.: x*(-6+x^4+7*x^3+4*x^2-3*x)/(-1+x^3+x^2) [From Maksym Voznyy (voznyy(AT)mail.ru), Aug 11 2009]
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CROSSREFS
| Cf. A068930 for incongruent tilings, A068920 for more info.
Sequence in context: A126445 A033326 A068996 * A106224 A129203 A083946
Adjacent sequences: A068921 A068922 A068923 * A068925 A068926 A068927
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KEYWORD
| easy,nonn
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AUTHOR
| Dean Hickerson (dean.hickerson(AT)yahoo.com), Mar 11 2002
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EXTENSIONS
| G.f. proposed by Maksym Voznyy checked and corrected by R. J. Mathar, Sep 16 2009.
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