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Search: id:A006961
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| A006961 |
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Mappings from n points to themselves with in-degree <= 2.
(Formerly M2584)
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+0
4
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| 1, 1, 3, 6, 15, 31, 75, 164, 388, 887, 2092, 4884, 11599, 27443, 65509, 156427, 375263
(list; graph; listen)
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OFFSET
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0,3
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
N. G. de Bruijn and D. A. Klarner, Multisets of aperiodic cycles, SIAM J, Algeb. Discrete Meth., 3 (1982), 359-368.
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CROSSREFS
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Cf. A006961.
Sequence in context: A034739 A097941 A117161 this_sequence A034740 A152167 A105476
Adjacent sequences: A006958 A006959 A006960 this_sequence A006962 A006963 A006964
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KEYWORD
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nonn,easy,nice
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AUTHOR
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Simon Plouffe (simon.plouffe(AT)gmail.com)
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