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Search: id:A112849
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| A112849 |
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Number of congruence classes (epimorphisms/vertex partitionings induced by graph endomorphisms) of undirected cycles of even length: |C(C_2n)|. |
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+0
2
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| 1, 4, 11, 36, 127, 463, 1717, 6436, 24311, 92379, 352717, 1352079, 5200301, 20058301
(list; graph; listen)
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OFFSET
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1,2
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REFERENCES
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M. A. Michels, About The Structure of Graph Endomorphisms, Diploma thesis, University of Oldenburg, Germany, 2005
M. A. Michels and U. Knauer, The congruence classes of paths and cycles, Discrete Math., 309 (2009), 5352-5359. [From N. J. A. Sloane, Sep 15 2009]
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FORMULA
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|C(C_2n)| = 1 + (1/2)*binomial(2n-1, n-1) + (1/2)*binomial(2n-1, n)
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CROSSREFS
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Cf. A112850.
Sequence in context: A149241 A149242 A149243 this_sequence A149244 A149245 A054105
Adjacent sequences: A112846 A112847 A112848 this_sequence A112850 A112851 A112852
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KEYWORD
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easy,nonn,more
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AUTHOR
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Martin Alexander Michels (martinmichels(AT)t-online.de), Sep 24 2005
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