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A058889
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Arrange binary trees in natural sequential order (see examples); sequence gives numbers of nodes.
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0
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1, 2, 3, 3, 4, 4, 4, 5, 5, 6, 4, 4, 5, 5, 6, 6, 6, 5, 5, 6, 6, 7, 7, 7, 7, 8, 5, 5, 6, 6, 7, 7, 7, 7, 8, 8, 8, 5, 5, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8, 8, 6, 6, 7, 7, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 10, 6, 6, 7, 7, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 10, 10, 10, 7, 7, 8, 8, 9, 9, 9, 9, 10, 10, 10, 10, 10, 10, 11, 11, 11
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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EXAMPLE
| The trees are x, (x,x), (x,(x,x)), ((x,x),x), ((x,x),(x,x)), (x,(x,(x,x))), ((x,(x,x)),x), ((x,x),(x,(x,x))), ((x,(x,x)),(x,x)), ((x,(x,x)),(x,(x,x))) (x,((x,x),x)), (((x,x),x),x), ((x,x)((x,x),x)), (((x,x),x),(x,x)), ((x,(xx)), ((x,x),x)),...
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CROSSREFS
| Cf. A000108.
Sequence in context: A156077 A189641 A189672 * A166724 A110862 A104257
Adjacent sequences: A058886 A058887 A058888 * A058890 A058891 A058892
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KEYWORD
| nonn,nice,easy
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AUTHOR
| Claude Lenormand (claude.lenormand(AT)free.fr), Jan 08 2001
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EXTENSIONS
| More terms from John W. Layman (layman(AT)math.vt.edu), Feb 03 2003
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