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Search: id:A123775
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| A123775 |
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Number of ways to build a contiguous building with n LEGO blocks of size 1x3 on top of a fixed block of the same size so that the building is symmetric after a rotation by 180 degrees. |
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+0
1
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| 2, 8, 24, 115, 451, 2474, 10377, 60048, 268402, 1600292, 7416480
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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The base block is not counted among the n and must be the only block in the bottom layer of the building
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REFERENCES
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M. Abrahamsen and S. Eilers, Efficient counting of LEGO buildings, in preparation
B. Durhuus and S. Eilers, On the entropy of LEGO, arXiv:math.CO/0504039
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LINKS
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S. Eilers, LEGO counts
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CROSSREFS
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Sequence in context: A150668 A150669 A157005 this_sequence A052624 A087982 A145238
Adjacent sequences: A123772 A123773 A123774 this_sequence A123776 A123777 A123778
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KEYWORD
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nonn
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AUTHOR
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Soren Eilers (eilers(AT)math.ku.dk), Oct 29 2006
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