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A304067
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Number of trees with n vertices rooted at a non-edge.
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2
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0, 0, 1, 3, 9, 27, 79, 233, 679, 1987, 5784, 16864, 49063, 142821, 415439, 1208761, 3516475, 10232428, 29778138, 86682119, 252382445, 735040515, 2141319946, 6239913801, 18188637903, 53033228465, 154674931182, 451247206423
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OFFSET
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1,4
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LINKS
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FORMULA
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EXAMPLE
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a(3)=1: the non-edge joins two leaves. a(4)=3: The non-edge joins two leaves of the star graph; or the non-edge joins the two leaves of the linear graph; or the non-edge joins a leaf with the node at distance 2.
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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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