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Search: id:A003082
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| A003082 |
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Number of multigraphs with 4 nodes and n edges.
(Formerly M2543)
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+0
7
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| 1, 1, 3, 6, 11, 18, 32, 48, 75, 111, 160, 224, 313, 420, 562, 738, 956, 1221, 1550, 1936, 2405, 2958, 3609, 4368, 5260, 6279, 7462, 8814, 10356, 12104, 14093, 16320, 18834, 21645, 24783, 28272, 32158, 36442, 41187, 46410, 52151, 58443, 65345, 72864
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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Also, expansion of Molien series for representation Sym^2(R^n) of the automorphism group of the lattice D_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).
CRC Handbook of Combinatorial Designs, 1996, p. 650.
J. L. Gross and J. Yellen, eds., Handbook of Graph Theory, CRC Press, 2004; p. 517.
F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 88, (4.1.19).
P. Sarnak and A. Stroembergsson, Minima of Epstein's zeta function and heights of flat tori, Preprint, 2005.
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LINKS
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T. D. Noe, Table of n, a(n) for n=0..1000
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FORMULA
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G.f.: (x^8-x^7+x^6+x^4+x^2-x+1)/((x-1)^6*(x+1)^2*(x^2+1)*(x^2+x+1)^2).
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CROSSREFS
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Cf. A001399, A014395-A014398.
Sequence in context: A123629 A053992 A052825 this_sequence A058053 A091094 A116100
Adjacent sequences: A003079 A003080 A003081 this_sequence A003083 A003084 A003085
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KEYWORD
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easy,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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Entry improved by comments from Vladeta Jovovic (vladeta(AT)eunet.rs), Dec 23 1999
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