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A165632
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Sizes of tatami-free rooms.
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6
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70, 88, 96, 108, 126, 130, 140, 150, 154, 160, 176, 180, 192, 198, 204, 208, 216, 228, 234, 238, 240, 250, 252, 260, 266, 270, 280, 286, 294, 300, 304, 308, 320, 322, 330, 336, 340, 348, 352, 360, 368, 372, 374, 378, 384, 390, 396, 400, 408, 414, 416, 418
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Even numbers s such that some rectangle of size s=r*c (r,c positive integers) cannot be tiled with tatamis of size 1x2 such that not more than 3 tatamis meet at any point.
The number of different rectangles of size a(n) which have this property is given in A165633(n).
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LINKS
| Project Euler, Problem 256: Tatami-Free Rooms
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FORMULA
| A165632 = { r*c in 2Z | A068920(r,c)=0 }
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EXAMPLE
| a(1)=70 because the rectangle of size 7x10 is the smallest that cannot be filled with 2x1 tiles without having 4 tiles meet in some point.
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CROSSREFS
| Cf. A068920.
Sequence in context: A118216 A114838 A036191 * A136117 A156718 A007621
Adjacent sequences: A165629 A165630 A165631 * A165633 A165634 A165635
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KEYWORD
| nonn
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AUTHOR
| M. F. Hasler (www.univ-ag.fr/~mhasler), Sep 26 2009
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