A054943 Number of connected oriented graphs on n nodes with an odd number of edges.
0, 2, 8, 320, 27584, 6991360, 5179178368, 11396324458496, 74944172892993536, 1476405354971707604992, 87208352627656970712229888, 15450530398306943408625302896640, 8211400756816955708062672318337859584
Offset: 1
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.
Programs
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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 *) -
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
Formula
Extensions
More terms from Vladeta Jovovic, Mar 11 2003