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Search: id:A161937
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| A161937 |
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The number of indirect isometries that are derangements of the (n-1)-dimensional facets of an n-cube. |
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+0
2
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| 1, 2, 15, 116, 1165, 13974, 195643, 3130280, 56345049
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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a(n) plays the same role as A145221 plays for the derangement numbers A000166.
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REFERENCES
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arXiv:0906.4253 : Moving faces to other places: Facet derangements. Authors: Gary Gordon, Elizabeth McMahon
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FORMULA
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a(n) = (b(n) + (-1)^(n+1))/2, where b(n) is sequence A000354, i.e., the number of (n-1)-dimensional facet derangements of an n-cube.
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EXAMPLE
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For a square, the 2 diagonal reflections are indirect edge derangements. For a 3-cube, the 15 rotary reflections are indirect face derangements.
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CROSSREFS
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A000354, A161936.
Sequence in context: A074622 A031507 A052861 this_sequence A074621 A052448 A127610
Adjacent sequences: A161934 A161935 A161936 this_sequence A161938 A161939 A161940
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KEYWORD
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easy,nonn
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AUTHOR
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Elizabeth McMahon, Gary Gordon (mcmahone(AT)lafayette.edu), Jun 29 2009
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