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Search: id:A097173
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| A097173 |
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Total number of green nodes among tricolored labeled trees on n nodes. |
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+0
5
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| 0, 2, 0, 48, 120, 4560, 35700, 1048992, 15514128, 456726240, 10073339100, 323266492560, 9361060088952, 336767513038320, 11913610172869860, 482920107426039360, 19998225191360977440, 909512248720724321472
(list; graph; listen)
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OFFSET
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1,2
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LINKS
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S. Coulomb and M. Bauer, On vertex covers, matchings and random trees
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FORMULA
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E.g.f.: A(x) = T(-T(x))^2, with T(x)=Sum[k=1..inf, A000169(k)/k!*x^k].
a(n) = -2 * n^(n-1) * Sum[l=1..n, (-l/n)^l*(1/l-1)*C(n, l)].
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CROSSREFS
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Cf. A097170, A097171, A097172, A097174, A000272.
Adjacent sequences: A097170 A097171 A097172 this_sequence A097174 A097175 A097176
Sequence in context: A120489 A012445 A012450 this_sequence A009493 A009718 A012420
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KEYWORD
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nonn
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AUTHOR
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Ralf Stephan, Jul 30 2004
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