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Search: id:A005976
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| A005976 |
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Number of unlabeled connected interval graphs with n nodes.
(Formerly M1487)
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+0
1
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| 1, 1, 2, 5, 15, 56, 250, 1328, 8069, 54962, 410330, 3317302, 28774874, 266242936, 2616100423, 27205605275, 298569256590, 3449309394415, 41854968275924, 532353636671777, 7083840662453415, 98443312509634266, 1426382369328881332
(list; graph; listen)
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OFFSET
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1,3
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REFERENCES
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P. J. Hanlon, Counting interval graphs. Trans. Amer. Math. Soc. 272 (1982), no. 2, 383-426.
P. J. Hanlon, personal communication.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
R. W. Robinson, Numerical implementation of graph counting algorithms, AGRC Grant, Math. Dept., Univ. Newcastle, Australia, 1980.
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LINKS
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R. W. Robinson, Table of n, a(n) for n = 1..30
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CROSSREFS
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Sequence in context: A137533 A121392 A119611 this_sequence A048192 A078792 A030934
Adjacent sequences: A005973 A005974 A005975 this_sequence A005977 A005978 A005979
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KEYWORD
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nonn,nice
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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a(21) onwards added by N. J. A. Sloane (njas(AT)research.att.com), Oct 19 2006 from the Robinson reference
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