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A123836
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Number of ways to build a contiguous building with n LEGO blocks of size 3 X 3 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
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OFFSET
| 1,2
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COMMENTS
| 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
| 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
| S. Eilers, LEGO counts
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CROSSREFS
| Sequence in context: A110462 A132375 A110360 * A141444 A061748 A159510
Adjacent sequences: A123833 A123834 A123835 * A123837 A123838 A123839
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KEYWORD
| nonn
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AUTHOR
| Soren Eilers (eilers(AT)math.ku.dk), Oct 29 2006
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