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 A165632 Sizes of tatami-free rooms. 6
 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; text; internal format)
 OFFSET 1,1 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). LINKS Table of n, a(n) for n=1..52. Project Euler, Problem 256: Tatami-Free Rooms FORMULA A165632 = { r*c in 2Z | A068920(r,c)=0 } 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. CROSSREFS Cf. A068920. Sequence in context: A345487 A114838 A036191 * A295807 A136117 A224553 Adjacent sequences: A165629 A165630 A165631 * A165633 A165634 A165635 KEYWORD nonn AUTHOR M. F. Hasler, Sep 26 2009 STATUS approved

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Last modified September 19 04:34 EDT 2024. Contains 376004 sequences. (Running on oeis4.)