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A000664 Number of graphs with n edges.
(Formerly M1400 N0545)
+0
5
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)
OFFSET

0,3

COMMENT

These are simple graphs, unlabeled, with no isolated nodes, but are not necessarily connected.

REFERENCES

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.

LINKS

P. J. Cameron, Sequences realized by oligomorphic permutation groups, J. Integ. Seqs. Vol. 3 (2000), #00.1.5.

FORMULA

Euler transform of A002905 (ignoring A002905(0)). - Franklin T. Adams-Watters (FrankTAW(AT)Netscape.net) Jul 03 2009

EXAMPLE

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)

CROSSREFS

Cf. A008406.

Adjacent sequences: A000661 A000662 A000663 this_sequence A000665 A000666 A000667

Sequence in context: A025245 A079223 A095892 this_sequence A067922 A095975 A006652

KEYWORD

nonn,nice

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com).

EXTENSIONS

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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Last modified November 9 12:23 EST 2009. Contains 166233 sequences.


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