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A019501
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Number of 7-ary search trees on n keys.
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0
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1, 1, 1, 1, 1, 1, 1, 7, 28, 84, 210, 462, 924, 1758, 3444, 7602, 19278, 52458, 142044, 368130, 905136, 2130198, 4895919, 11280885, 26685540, 65491062, 165584034, 423910572, 1080774261, 2717940687, 6731334225, 16494155097, 40308269022
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OFFSET
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0,8
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LINKS
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Table of n, a(n) for n=0..32.
J. A. Fill and R. P. Dobrow, The number of m-ary search trees on n keys, Combin. Probab. Comput. 6 (1997), 435-453.
Index entries for sequences related to rooted trees
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MAPLE
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A:= proc(n) option remember; if n=0 then 1 else convert(series(
add(x^i, i=0..5)+ x^6*A(n-1)^7, x=0, n+1), polynom) fi
end:
a:= n-> coeff(A(n), x, n):
seq(a(n), n=0..40); # Alois P. Heinz, Aug 22 2008
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MATHEMATICA
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A[n_] := A[n] = If[n==0, 1, Series[Sum[x^i, {i, 0, 5}] + x^6*A[n-1]^7, {x, 0, n+1}] // Normal]; a[n_] := Coefficient[A[n], x, n]; Table[a[n], {n, 0, 40}] (* Jean-François Alcover, Feb 19 2016, after Alois P. Heinz *)
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CROSSREFS
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Sequence in context: A000579 A290994 A049017 * A229887 A243741 A145456
Adjacent sequences: A019498 A019499 A019500 * A019502 A019503 A019504
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KEYWORD
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nonn
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AUTHOR
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James Fill (jimfill(AT)jhu.edu)
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EXTENSIONS
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More terms from Alois P. Heinz, Aug 22 2008
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STATUS
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approved
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