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A273656
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Number of forests of labeled rooted trees of height at most 1, with n labels, six of which are used for root nodes and any root may contain >= 1 labels.
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2
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203, 4718, 66808, 750120, 7370580, 66562188, 568136184, 4663350120, 37228965774, 291297376370, 2245876801168, 17126594554160, 129527848747752, 973416393927768, 7278979868039760, 54211596845506800, 402386221073227314, 2977842560384800878, 21977111826224423176
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OFFSET
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6,1
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LINKS
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FORMULA
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E.g.f.: x^6/6! * Sum_{j=0..6} Stirling2(6,j)*exp(x)^j.
a(n) = C(n,6) * Sum_{j=0..6} Stirling2(6,j) * j^(n-6).
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MAPLE
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a:= n-> binomial(n, 6)*add(Stirling2(6, j)*j^(n-6), j=0..6):
seq(a(n), n=6..40);
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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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