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A075217
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Number of polyiamonds with 2n cells that tile the plane by translation but not by 180-degree rotation (Conway criterion).
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10
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0, 0, 0, 0, 1, 22, 38, 504, 1468, 6945, 11046, 115186, 119496, 677774, 2013619
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,6
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COMMENTS
| Polyiamonds with an odd number of cells have different numbers of triangles with the two orientations and so cannot tile by translation.
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REFERENCES
| Branko Gruenbaum and G. C. Shephard, Tilings and Patterns. W. H. Freeman, New York, 1987, Section 9.4.
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LINKS
| Joseph Myers, Polyiamond tiling
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CROSSREFS
| Cf. A071332, A075216, A075218, A075219, A075220, A075221, A075222, A075223, A075224, A075199, A075208.
Sequence in context: A043196 A043976 A131196 * A116658 A188156 A026061
Adjacent sequences: A075214 A075215 A075216 * A075218 A075219 A075220
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KEYWORD
| hard,nonn
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AUTHOR
| Joseph Myers (jsm(AT)polyomino.org.uk), Sep 08 2002
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EXTENSIONS
| More terms from Joseph Myers (jsm(AT)polyomino.org.uk), Nov 11 2003
a(15) (30-iamonds) from Joseph Myers (jsm(AT)polyomino.org.uk), Nov 21 2010
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