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A007869 Complementary pairs of graphs on n nodes. Also unlabeled graphs with n nodes and an even number of edges. 11
1, 1, 2, 6, 18, 78, 522, 6178, 137352, 6002584, 509498932, 82545586656, 25251015686776, 14527077828617744, 15713242984902154384, 32000507852263779299344, 122967932076766466347469888 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..17.

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

Nevena Francetić, Sarada Herke, Ian M. Wanless, Parity of Sets of Mutually Orthogonal Latin Squares, arXiv:1703.04764 [math.CO], 2017. See Section 4.1.

MATHEMATICA

Needs["Combinatorica`"]; Table[Total[Table[NumberOfGraphs[n, m], {m, 0, Binomial[n, 2], 2}]], {n, 1, 15}]  (* Geoffrey Critzer, Oct 20 2012 *)

CROSSREFS

Average of A000088 and A000171, the latter interspersed with zeros.

Cf. A054960 for graphs with an odd number of edges.

Sequence in context: A113844 A266858 A141580 * A263915 A144557 A273001

Adjacent sequences:  A007866 A007867 A007868 * A007870 A007871 A007872

KEYWORD

nonn,nice

AUTHOR

Peter J. Cameron

EXTENSIONS

More terms from Vladeta Jovovic, Jul 19 2000

Mathematica program modified by Harvey P. Dale, Aug 08 2013

STATUS

approved

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Last modified February 24 05:37 EST 2018. Contains 299597 sequences. (Running on oeis4.)