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Search: id:A000664
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| A000664 |
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Number of graphs with n edges.
(Formerly M1400 N0545)
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+0
5
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| 1, 1, 2, 5, 11, 26, 68, 177, 497, 1476, 4613, 15216, 52944, 193367, 740226, 2960520, 12334829, 53394755, 239544624, 1111261697, 5320103252, 26237509076, 133087001869, 693339241737, 3705135967663, 20286965943329, 113694201046379
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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These are simple graphs, unlabeled, with no isolated nodes, but are not necessarily connected.
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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. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
W. Oberschelp, Kombinatorische Anzahlbestimmungen in Relationen, Math. Ann., 174 (1967), 53-78.
J. Riordan, An Introduction to Combinatorial Analysis, Wiley, 1958, p. 146.
M. L. Stein and P. R. Stein, Enumeration of Linear Graphs and Connected Linear Graphs up to $p = 18$ Points. Report LA-3775, Los Alamos Scientific Laboratory of the University of California, Los Alamos, NM, Oct 1967.
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LINKS
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P. J. Cameron, Sequences realized by oligomorphic permutation groups, J. Integ. Seqs. Vol. 3 (2000), #00.1.5.
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FORMULA
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Euler transform of A002905 (ignoring A002905(0)). - Franklin T. Adams-Watters (FrankTAW(AT)Netscape.net) Jul 03 2009
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EXAMPLE
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n=1: o-o (1)
n=2: o-o o-o, o-o-o (2)
n=3: o-o o-o o-o, o-o-o o-o, o-o-o-o, Y, triangle (5)
n=4: o-o o-o o-o o-o, o-o-o o-o o-o, o-o-o o-o-o, o-o o-o-o-o, o-o Y, o-o triangle,
o-o-o-o-o, >o-o-o, ><, square, triangle with tail (11)
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CROSSREFS
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Cf. A008406.
Adjacent sequences: A000661 A000662 A000663 this_sequence A000665 A000666 A000667
Sequence in context: A025245 A079223 A095892 this_sequence A067922 A095975 A006652
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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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More terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Jan 08 2000, Aug 14 2007
Edited by N. J. A. Sloane (njas(AT)research.att.com), Feb 26 2008
Example for n=2 corrected by Adrian Falcone (falcone(AT)gmail.com), Jan 28 2009
Zero term inserted by Franklin T. Adams-Watters (FrankTAW(AT)Netscape.net), Jul 03 2009
a(25)-a(26) from Max Alekseyev (maxale(AT)gmail.com), Sep 19 2009
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