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Search: id:A004108
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| A004108 |
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Number of n-node connected graphs without endpoints.
(Formerly M2910)
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+0
12
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| 1, 0, 1, 3, 11, 61, 507, 7442, 197772, 9808209, 902884343, 153723152913, 48443147912137, 28363697921914475, 30996525982586676021, 63502034385272108655525, 244852545421597419740767106, 1783161611489937453151313949442
(list; graph; listen)
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OFFSET
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1,4
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COMMENT
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Also number of n-node unlabeled connected mating graphs, cf. A006024 and A092430 (Conjectured by V. Jovovic, proved by G. Kilibarda). Oct 07, 2004
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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).
F. Harary and E. Palmer, Graphical Enumeration, (1973), formula (8.7.11).
Goran Kilibarda, "Enumeration of unlabeled mating graphs", Belgrade, 2004, to be published.
R. W. Robinson, personal communication.
R. W. Robinson, Numerical implementation of graph counting algorithms, AGRC Grant, Math. Dept., Univ. Newcastle, Australia, 1977.
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LINKS
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R. W. Robinson, Table of n, a(n) for n = 1..26
Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
Goran Kilibarda, Enumeration of Unlabeled Mating Graphs, Graphs and Combinatorics, Volume 23, Number 2 / April, 2007, pp. 183-199.
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CROSSREFS
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Cf. A059166 (n-node connected labeled graphs without endpoints), A059167 (n-node labeled graphs without endpoints), A004110 (n-node unlabeled graphs without endpoints).
Cf. A092430 (n-node labeled connected mating graphs).
Sequence in context: A127516 A095237 A024528 this_sequence A069725 A096655 A030226
Adjacent sequences: A004105 A004106 A004107 this_sequence A004109 A004110 A004111
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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