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A000552
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Number of labeled rooted trees of height 3 with n nodes.
(Formerly M5159 N2241)
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2
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24, 300, 3360, 38850, 475776, 6231960, 87530400, 1316954430, 21173760960, 362670636900, 6596214691248, 126980000240730, 2579214238608000, 55118036257959600, 1235935135837111104, 29009023670878484598
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OFFSET
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4,1
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REFERENCES
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N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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FORMULA
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E.g.f.: x*(exp(x*exp(x*exp(x)))-exp(x*exp(x))). - Vladeta Jovovic, Jan 29 2008
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MAPLE
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ht := proc(m) local i; [ T0, {seq(T.i=Prod(Z, Set(T.(i+1))), i=0..m-1), T.m=Z}, labeled ] end: M[ 5159 ] := n -> count(ht(3), size=n)-count(ht(2), size=n): seq(M[ 5159 ](n), n=4..19);
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MATHEMATICA
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With[{nn=20}, Drop[CoefficientList[Series[x(Exp[x Exp[x Exp[x]]]- Exp[x Exp[x]]), {x, 0, nn}], x]Range[0, nn]!, 4]] (* Harvey P. Dale, Oct 01 2011 *)
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CROSSREFS
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KEYWORD
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nonn,easy,nice
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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