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 A053598 Number of n-node unlabeled digraphs without isolated nodes. 3
 1, 0, 2, 13, 202, 9390, 1531336, 880492496, 1792477159408, 13026163465206704, 341247403996148180800, 32522568124623933138617088, 11366712907916015518547782806784, 14669074325967499043636521641422216704, 70315641946149306808455637518883828774996992 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Equals first differences of A000273. LINKS Alois P. Heinz, Table of n, a(n) for n = 0..35 FORMULA O.g.f.: A(x)*(1-x) where A(x) is o.g.f. for A000273. - Geoffrey Critzer, Oct 09 2012 MATHEMATICA Needs["Combinatorica`"]; nn=15; s=Sum[NumberOfDirectedGraphs[n]x^n, {n, 0, nn}]; CoefficientList[Series[s (1-x), {x, 0, nn}], x]  (* Geoffrey Critzer, Oct 09 2012 *) Join[{1}, Table[GraphPolynomial[n, x, Directed] /. x -> 1, {n, 0, 15}] // Differences] (* Jean-François Alcover, Feb 04 2015 *) CROSSREFS Cf. A002494. Sequence in context: A049512 A003507 A003085 * A193550 A102585 A227746 Adjacent sequences:  A053595 A053596 A053597 * A053599 A053600 A053601 KEYWORD nonn,nice AUTHOR Vladeta Jovovic, Apr 10 2000 STATUS approved

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Last modified February 17 12:10 EST 2019. Contains 320219 sequences. (Running on oeis4.)