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Search: id:A076616
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| A076616 |
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Number of permutations of {1,2,...,n} that result in a binary search tree (when elements of the permutation are inserted in that order) of height n-1 (i.e. the second largest possible height). |
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+0
2
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OFFSET
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1,3
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EXAMPLE
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a(3) = 2 because only the permutations 1 2 3 and 3 2 1 result in result in a search tree of height 2 (notice we count empty external nodes in determining the height). The largest such trees are of height 3.
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CROSSREFS
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Sequence in context: A123791 A152665 A061608 this_sequence A127276 A110048 A094505
Adjacent sequences: A076613 A076614 A076615 this_sequence A076617 A076618 A076619
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KEYWORD
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nonn
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AUTHOR
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Jeffrey Shallit (shallit(AT)graceland.uwaterloo.ca), Oct 22 2002
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