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A052512
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Number of labeled trees of height 2.
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5
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0, 1, 2, 9, 40, 205, 1176, 7399, 50576, 372537, 2936080, 24617131, 218521128, 2045278261, 20112821288, 207162957135, 2228888801056, 24989309310961, 291322555295904, 3524580202643155, 44176839081266360
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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LINKS
| INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 58
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FORMULA
| E.g.f.: x*exp(x*exp(x))
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MAPLE
| spec := [S, {S=Prod(Z, Set(T1)), T2=Z, T1=Prod(Z, Set(T2))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
| Sequence in context: A107979 A021001 A038112 * A166554 A038156 A052846
Adjacent sequences: A052509 A052510 A052511 * A052513 A052514 A052515
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KEYWORD
| easy,nonn
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AUTHOR
| encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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