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A052513
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Number of labeled trees of height 3.
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0
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0, 1, 2, 9, 64, 505, 4536, 46249, 526352, 6604497, 90466480, 1341571561, 21392282088, 364715915161, 6616327512536, 127187163197865, 2581443127409056, 55143025567270561, 1236226458392407008
(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 59
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FORMULA
| E.g.f.: x*exp(x*exp(x*exp(x)))
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MAPLE
| spec := [S, {S=Prod(Z, Set(T1)), T2=Prod(Z, Set(T3)), T3=Z, T1=Prod(Z, Set(T2))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
| Sequence in context: A167913 A076944 A074181 * A024720 A094100 A185897
Adjacent sequences: A052510 A052511 A052512 * A052514 A052515 A052516
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KEYWORD
| easy,nonn
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AUTHOR
| encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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