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 A054942 Number of connected oriented graphs on n nodes with an even number of edges. 0
 1, 0, 12, 304, 27664, 6990848, 5179182272, 11396324423680, 74944172893348096, 1476405354971703541760, 87208352627656970763963392, 15450530398306943408624578330624, 8211400756816955708062672329408385024 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS V. A. Liskovets, Some easily derivable sequences, J. Integer Sequences, 3 (2000), #00.2.2. MATHEMATICA nn = 15; g[z] := Sum[(1 + 2 u)^Binomial[n, 2] z^n/n!, {n, 0, nn}]; Drop[ Map[Total[#[[1 ;; Binomial[nn, 2] + 1 ;; 2]]]&, Range[0, nn]!CoefficientList[ Series[Log[g[z]], {z, 0, nn}], {z, u}]], 1] (* Geoffrey Critzer, Jul 28 2016 *) CROSSREFS Sequence in context: A245915 A109867 A014130 * A052795 A263668 A053064 Adjacent sequences:  A054939 A054940 A054941 * A054943 A054944 A054945 KEYWORD nonn,easy AUTHOR N. J. A. Sloane, May 24 2000 EXTENSIONS More terms from Vladeta Jovovic, Mar 11 2003 STATUS approved

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