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 A054943 Number of connected oriented graphs on n nodes with an odd number of edges. 2
 0, 2, 8, 320, 27584, 6991360, 5179178368, 11396324458496, 74944172892993536, 1476405354971707604992, 87208352627656970712229888, 15450530398306943408625302896640, 8211400756816955708062672318337859584 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Andrew Howroyd, Table of n, a(n) for n = 1..50 V. A. Liskovets, Some easily derivable sequences, J. Integer Sequences, 3 (2000), #00.2.2. FORMULA a(n) = (A054941(n) + (-1)^n*A000831(n-1))/2. - Andrew Howroyd, Sep 10 2018 MATHEMATICA nn = 15; g[z] :=Sum[(1 + 2 u)^Binomial[n, 2] z^n/n!, {n, 0, nn}]; Drop[ Map[Total[#[[2 ;; Binomial[nn, 2] + 1 ;; 2]]]&, Range[0, nn]!CoefficientList[ Series[Log[g[z]], {z, 0, nn}], {z, u}]], 1] (* Geoffrey Critzer, Jul 28 2016 *) PROG (PARI) seq(n)={my(A=O(x*x^n)); Vec(serlaplace(log(sum(k=0, n, 3^binomial(k, 2)*x^k/k!) + A) - log(cos(x + A) + sin(x + A)))/2, -n)} \\ Andrew Howroyd, Sep 10 2018 CROSSREFS Cf. A000831, A054941, A054942. Sequence in context: A013086 A012536 A012541 * A013135 A012999 A013003 Adjacent sequences: A054940 A054941 A054942 * A054944 A054945 A054946 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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Last modified February 26 06:43 EST 2024. Contains 370335 sequences. (Running on oeis4.)