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A092430
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Number of n-node labeled connected mating graphs, cf. A006024.
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11
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1, 1, 25, 438, 18388, 1409674, 206682994, 58152537184, 31715884061624, 33827568738189576, 71066571962396085656, 295645506683051376527648, 2444503529745123474354656720, 40269655263141217619453414445968
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OFFSET
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2,3
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COMMENTS
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Number of n-node unlabeled connected mating graphs = number of n-node unlabeled connected graphs without endpoints, n>2; cf. A004108.
The number of graphs of this type with n>=1 nodes and 1<=k<=n components defines the triangle
0;
1,0;
1,0,0;
25,3,0,0;
438,10,0,0,0;
18388,385,15,0,0,0;
1409674,10073,105,0,0,0,0;
206682994,561267,5530,105,0,0,0,0;
58152537184,53672556,197344,1260,0,0,0,0,0;
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REFERENCES
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Goran Kilibarda, "Enumeration of unlabeled mating graphs", Belgrade, 2004, to be published.
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LINKS
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FORMULA
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E.g.f.: log((Sum_{n>=0} 2^binomial(n, 2)*log(1+x)^n/n!)/(1+x)).
a(n) = A079306(n) + (-1)^n*(n-1)!. (End)
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PROG
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(PARI) a(n)={n!*polcoef(log(sum(i=0, n, 2^binomial(i, 2)*log(1+x + O(x*x^n))^i/i!)/(1+x)), n)} \\ Andrew Howroyd, Sep 09 2018
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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