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A159768
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Number of n-leaf binary trees that do not contain (()(()(()((()())())))) as a subtree.
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2
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1, 1, 2, 5, 14, 41, 124, 385, 1221, 3939, 12886, 42648, 142544, 480459, 1631287, 5574073, 19153815, 66146259, 229452587, 799140681, 2793373937, 9796395680, 34459558856, 121548541383, 429823475811, 1523511450184, 5411789548439
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OFFSET
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1,3
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COMMENTS
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By 'binary tree' we mean a rooted, ordered tree in which each vertex has either 0 or 2 children.
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LINKS
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FORMULA
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G.f. f(x) satisfies -x f(x)^3 + (x-1) x f(x)^2 + (x-1)^2 f(x) + (x-1) x = 0.
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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