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A088720
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Unique monotone sequence satisfying a(a(a(n)))=2n.
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2
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4, 5, 6, 8, 9, 10, 11, 12, 14, 16, 17, 18, 19, 20, 21, 22, 23, 24, 26, 28, 30, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 50, 52, 54, 56, 58, 60, 62, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89
(list; graph; refs; listen; history; internal format)
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OFFSET
| 3,1
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COMMENTS
| For k >= 1 and m >= 2, a monotone a(n) such that a^(k+1)(n) = mn is unique only when m = 2 or (k,m) = (1,3).
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FORMULA
| For a^(k+1)(n) = 2n, we have for (k+1)2^m <= n <= (2k+1)2^m, a(n) = n+2^m; for (2k+1)2^m <= n <= (2k+2)2^m, a(n) = 2n-2k.2^m.
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EXAMPLE
| a(a(a(3)))=a(a(4))=a(5)=6.
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CROSSREFS
| Cf. A007378, A003605, A088721.
Sequence in context: A063673 A105737 A033597 * A134848 A061578 A023851
Adjacent sequences: A088717 A088718 A088719 * A088721 A088722 A088723
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KEYWORD
| easy,nonn
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AUTHOR
| C.L.Mallows (colinm(AT)research.avayalabs.com), Oct 16 2003
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EXTENSIONS
| More terms from John W. Layman (layman(AT)math.vt.edu), Oct 18 2003
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