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Search: id:A057973
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| A057973 |
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Number of polybricks: number of ways to arrange n 1 X 2 "bricks" in a wall (see illustrations). |
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4
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| 1, 2, 5, 16, 55, 225, 949, 4269, 19500, 91115, 429742, 2047660, 9820197, 47383255, 229725560, 1118568692, 5466616025, 26804560282, 131817042605, 649952289243
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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The tiling of bricks is topologically the same as that by regular hexagons and this sequence can also be seen as counting polyhexes where two polyhexes are equivalent iff they are related by a symmetry that is also a symmetry of the tiling by bricks.
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REFERENCES
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Other references on polyforms are: www.mathpuzzle.com, Solomon W. Golomb, Ed Pegg, Eric Weisstein, David A. Klarner (Packing rectangles) and Michael Reid [These references should be expanded! - N. J. A. Sloane (njas(AT)research.att.com)]
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LINKS
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Brendan Owen and Livio Zucca, Polyform generation
Brendan Owen and Livio Zucca, The 16 polybricks of order 4
N. J. A. Sloane, The polybricks of orders 1, 2 and 3
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CROSSREFS
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Sequence in context: A066642 A019988 A137732 this_sequence A102461 A052708 A149973
Adjacent sequences: A057970 A057971 A057972 this_sequence A057974 A057975 A057976
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KEYWORD
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nonn,nice
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AUTHOR
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Warren Power (wjpnply(AT)hotmail.com), Oct 21 2000
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EXTENSIONS
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More terms from Don Reble (djr(AT)nk.ca), Nov 01 2001
Corrected and extended by Joseph Myers (jsm(AT)polyomino.org.uk), Sep 21 2002
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