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A102423
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Start at x=2n+1, iterate the map x -> A337349(x); sequence gives smallest number in the resulting cycle, or -1 if the trajectory never cycles.
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4
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1, 1, 1, 1, 1, 1, 1, 17, 17, 17, 1, 1, 1, 17, 1, 1, 1, 1, 1, 1, 1, 17, 1, 1, 1, 1, 1, 1, 1, 1, 17, 1, 1, 1, 17, 1, 1, 17, 17, 1, 1, 1, 1, 1, 1, 1, 1, 17, 17, 1, 1, 1, 1, 17, 17, 1, 1, 1, 1, 1, 17, 17, 1, 1, 1, 1, 1, 17, 17, 1, 1, 1, 1, 1, 1, 1, 17, 1, 1, 1, 1, 1, 1, 1, 17, 17, 17, 1, 1, 1, 1, 1, 1, 1, 1
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OFFSET
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0,8
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COMMENTS
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See A102421 and A337349 for further comments.
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LINKS
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David A. Corneth, Table of n, a(n) for n = 0..9999
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MATHEMATICA
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nextx[x_Integer] := Block[{a = x}, a = 3a + 1; While[EvenQ@a, a /= 2]; a = 3a - 1; While[EvenQ@a, a /= 2]; a]; f[n_] := NestWhile[nextx, n, FreeQ[{1, 17, 19, 43, 97, 109, 61}, # ] &]; Table[ If[ f[2n + 1] == 1, 1, 17], {n, 0, 94}] (* Robert G. Wilson v, Sep 20 2006; added 61 to comparison set used for detecting cycles, William P. Orrick, Aug 24 2020; should be "!" prefixing MemberQ, changed to FreeQ, Ray Chandler, Aug 28 2020 *)
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CROSSREFS
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Cf. A102421, A122563 (iterations to enter cycle), A337349.
Sequence in context: A172091 A291370 A291432 * A010856 A291515 A216436
Adjacent sequences: A102420 A102421 A102422 * A102424 A102425 A102426
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane, based on email from Dan Asimov (dasimov(AT)earthlink.net), Sep 15 2006
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EXTENSIONS
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More terms from Robert G. Wilson v, Sep 20 2006
Replaced A102421 by A337349 in NAME. - R. J. Mathar, Aug 24 2020
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STATUS
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approved
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