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A052120
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Number of 3-valent trees (= boron trees or binary trees) with n nodes.
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1
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1, 1, 0, 1, 0, 1, 0, 1, 0, 2, 0, 2, 0, 4, 0, 6, 0, 11, 0, 18, 0, 37, 0, 66, 0, 135, 0, 265, 0, 552, 0, 1132, 0, 2410, 0, 5098, 0, 11020, 0, 23846, 0
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OFFSET
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1,10
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COMMENTS
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Trees with n nodes each of valency either 1 or 3.
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LINKS
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Table of n, a(n) for n=1..41.
Eric Weisstein's World of Mathematics, Cayley Tree.
Eric Weisstein's World of Mathematics, Trivalent Tree
Index entries for sequences related to trees
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CROSSREFS
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See A000672, the subsequence of even-numbered terms, which is the main entry for this sequence, for more terms, references, etc.
Sequence in context: A201863 A035385 A051629 * A179461 A029186 A072680
Adjacent sequences: A052117 A052118 A052119 * A052121 A052122 A052123
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KEYWORD
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nonn,easy
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AUTHOR
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N. J. A. Sloane.
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STATUS
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approved
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