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Search: id:A121645
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| A121645 |
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Consider trajectory of n under the "x->2x+1" map; sequence gives number of steps until a non-squarefree number is reached. |
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+0
2
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| 5, 13, 4, 0, 12, 2, 3, 0, 0, 4, 11, 0, 1, 15, 2, 0, 5, 0, 5, 0, 3, 1, 10, 0, 0, 13, 0, 0, 14, 4, 1, 0, 2, 3, 4, 0, 1, 10, 4, 0, 7, 2, 2, 0, 0, 3, 9, 0, 0, 0, 2, 0, 12, 0, 5, 0, 4, 1, 13, 0, 3, 1, 0, 0, 16, 4, 1, 0, 2, 3, 3, 0, 1, 14, 0, 0, 9, 2, 3, 0, 0, 5, 6, 0, 1, 5, 1, 0, 54, 0, 3, 0, 2, 1, 8, 0, 3, 0, 0
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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For n up to 2000, the maximal length is 95, for n=1574.
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LINKS
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Zak Seidov, Table of n, a(n) for n = 1..2000
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EXAMPLE
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If initial x is not squarefree, sequence has zero length (this is denoted by "-"):
{1,3,7,15,31},
{2,5,11,23,47,95,191,383,767,1535,3071,6143,12287},
{3,7,15,31},
{4-},
{5,11,23,47,95,191,383,767,1535,3071,6143,12287},
{6,13},
{7,15,31},
{8-},
{9-},
{10,21,43,87},
{11,23,47,95,191,383,767,1535,3071,6143,12287},
{12-},
{13},
{14,29,59,119,239,479,959,1919,3839,7679,15359,30719,61439,122879,245759},
{15,31},
{16-},
{17,35,71,143,287},
{18-},
{19,39,79,159,319},
{20}.
Lengths are: 5,13,4,0,12,2,3,0,0,4,11,0,1,15,2,0,5,0,5,0,...
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CROSSREFS
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Sequence in context: A035412 A065865 A088618 this_sequence A057691 A089619 A094473
Adjacent sequences: A121642 A121643 A121644 this_sequence A121646 A121647 A121648
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KEYWORD
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nonn
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AUTHOR
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Zak Seidov (zakseidov(AT)yahoo.com), Aug 13 2006
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