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A086345 Number of connected oriented graphs (i.e., connected directed graphs with no bidirected edges) on n nodes. 9
1, 1, 1, 5, 34, 535, 20848, 2120098, 572849763, 415361983540, 815590925440865, 4373589784210012634, 64535461714821630421106, 2637732191356603658136444467, 300363258297687600380548275359231 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,4
LINKS
Musa Demirci, Ugur Ana, and Ismail Naci Cangul, Properties of Characteristic Polynomials of Oriented Graphs, Proc. Int'l Conf. Adv. Math. Comp. (ICAMC 2020) Springer, see p. 61.
Chathura Kankanamge, Multiple Continuous Subgraph Query Optimization Using Delta Subgraph Queries, Master Maths Thesis, Univ. of Waterloo, 2018.
Eric Weisstein's World of Mathematics, Oriented Graph
FORMULA
Inverse Euler transform of A001174. - Andrew Howroyd, Nov 03 2017
MATHEMATICA
permcount[v_] := Module[{m = 1, s = 0, k = 0, t}, For[i = 1, i <= Length[v], i++, t = v[[i]]; k = If[i > 1 && t == v[[i - 1]], k + 1, 1]; m *= t*k; s += t]; s!/m];
edges[v_] := Sum[GCD[v[[i]], v[[j]]], {i, 2, Length[v]}, {j, 1, i - 1}] + Total @ Quotient[v - 1, 2];
a1174[n_] := Module[{s = 0}, Do[s += permcount[p]*3^edges[p], {p, IntegerPartitions[n]}]; s/n!];
b = Array[a1174, 15];
mob[m_, n_] := If[Mod[m, n] == 0, MoebiusMu[m/n], 0];
EULERi[b_] := Module[{a, c, i, d}, c = {}; For[i = 1, i <= Length[b], i++, c = Append[c, i*b[[i]] - Sum[c[[d]]*b[[i - d]], {d, 1, i - 1}]]]; a = {}; For[i = 1, i <= Length[b], i++, a = Append[a, (1/i)*Sum[mob[i, d]*c[[d]], {d, 1, i}]]]; Return[a]];
A086345 = EULERi[b] (* Jean-François Alcover, Jul 06 2018, after Andrew Howroyd *)
CROSSREFS
Cf. A054941 (labeled case), A001174, A281446 (multisets).
Sequence in context: A211037 A130607 A211042 * A295545 A309534 A348375
KEYWORD
nonn
AUTHOR
Eric W. Weisstein, Jul 16 2003
EXTENSIONS
More terms from Vladeta Jovovic, Jul 19 2003
a(0)=1 prepended by Andrew Howroyd, Sep 09 2018
STATUS
approved

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Last modified April 25 09:49 EDT 2024. Contains 371967 sequences. (Running on oeis4.)