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A068922
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Number of ways to tile a 3 X 2n room with 1x2 Tatami mats. At most 3 Tatami mats may meet at a point.
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6
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3, 4, 6, 10, 16, 26, 42, 68, 110, 178, 288, 466, 754, 1220, 1974, 3194, 5168, 8362, 13530, 21892, 35422, 57314, 92736, 150050, 242786, 392836, 635622, 1028458, 1664080, 2692538, 4356618, 7049156, 11405774, 18454930, 29860704, 48315634
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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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 >= 2, a(n) = 2*F(n+1), where F(n)=A000045(n) is the n-th Fibonacci number.
G.f.: x*(x^2-x-3)/(x^2+x-1) [From Maksym Voznyy (voznyy(AT)mail.ru), Aug 11 2009]
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CROSSREFS
| Cf. A068928 for incongruent tilings, A068920 for more info.
Essentially the same as A006355.
Sequence in context: A114736 A099417 A139463 * A032408 A018908 A052548
Adjacent sequences: A068919 A068920 A068921 * A068923 A068924 A068925
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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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