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Search: id:A029768
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| A029768 |
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Number of increasing mobiles with n elements. |
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+0
7
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| 0, 1, 1, 2, 7, 36, 245, 2076, 21059, 248836, 3356609, 50896380, 856958911, 15864014388, 320245960333, 7001257954796, 164792092647355, 4154906594518116, 111719929072986521, 3191216673497748444
(list; graph; listen)
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OFFSET
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0,4
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COMMENT
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In an increasing rooted tree, nodes are numbered and numbers increase as you move away from root.
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REFERENCES
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F. Bergeron, G. Labelle and P. Leroux, Combinatorial Species and Tree-Like Structures, Camb. 1998, p. 392.
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LINKS
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Index entries for sequences related to mobiles
C. G. Bower, Transforms
C. G. Bower, Transforms (2)
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FORMULA
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Bergeron et al. give several formulae. Shifts left under "CIJ" (necklace, indistinct, labeled) transform.
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MATHEMATICA
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Multinomial1[list_] := Apply[Plus, list]!/Apply[Times, (#1! & ) /@ list]; a[1]=1; a[n_]/; n>=2 := a[n] = Sum[Map[Multinomial1[ # ]Product[Map[a, # ]]/Length[ # ]&, Compositions[n-1]]]; Table[a[n], {n, 8}] - David Callan (callan(AT)stat.wisc.edu), Nov 29 2007
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CROSSREFS
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Cf. A032220, A038037, A055356.
Sequence in context: A088715 A088313 A095793 this_sequence A167199 A007889 A125033
Adjacent sequences: A029765 A029766 A029767 this_sequence A029769 A029770 A029771
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KEYWORD
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nonn,easy,eigen,nice
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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More terms from Christian G. Bower (bowerc(AT)usa.net)
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