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Search: id:A019498
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| A019498 |
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Number of 4-ary search trees on n keys. |
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+0
1
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| 1, 1, 1, 1, 4, 10, 20, 47, 128, 340, 868, 2275, 6188, 16922, 46112, 126613, 351568, 981622, 2747876, 7723250, 21811856, 61828886, 175752728, 500984606, 1432111244, 4104175970, 11787811340, 33926475162, 97837209036, 282662156478
(list; graph; listen)
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OFFSET
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0,5
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REFERENCES
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J. A. Fill and R. P. Dobrow, The number of m-ary search trees on n keys, Combin. Probab. Comput. 6 (1997), 435-453.
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LINKS
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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 (sum (x^i, i=0..2)+ x^3*A(n-1)^4, x=0, n+1), polynom) fi end: a:= n-> coeff (A(n), x, n): seq (a(n), n=0..40); [From Alois P. Heinz (heinz(AT)hs-heilbronn.de), Aug 22 2008]
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CROSSREFS
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Sequence in context: A100354 A048008 A048019 this_sequence A015889 A020149 A056412
Adjacent sequences: A019495 A019496 A019497 this_sequence A019499 A019500 A019501
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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 (heinz(AT)hs-heilbronn.de), Aug 22 2008
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