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Search: id:A087717
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| A087717 |
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Start with x=n, then iterate the mapping x->f(x) with f(x)=x/d if d<x, otherwise f(x)=2*x-1, where d is the smallest divisor d>1 of x. If this iteration leads to a fixed point then a(n) is the value of that fixed point. If the iteration leads to a cycle, a(n) is the smallest value in the cycle. If the iteration never becomes periodic then a(n)=0. |
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| 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 19, 3, 3, 3, 3, 3, 3, 3, 3, 3, 19, 3, 3, 3, 3, 3, 3, 3, 19, 19, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 19, 19, 3, 3, 3, 3, 3, 3, 3, 3, 19, 3, 3, 3, 3, 3, 19, 19, 3, 19, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 19, 3, 3, 3, 3, 3, 3, 3, 19, 3, 3, 3, 3, 3
(list; graph; listen)
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OFFSET
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2,1
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COMMENT
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Conjecture. The iteration given in the definition above always leads to the 3-cycle {3,5,9,3} or the 6-cycle {19,37,73,145,29,57,19}, thus a(n) takes on only the values 3 or 19 for n=2,3,4,.... This has been verified to n=1000000.
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CROSSREFS
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Sequence in context: A010701 A122553 A032552 this_sequence A053444 A130635 A135717
Adjacent sequences: A087714 A087715 A087716 this_sequence A087718 A087719 A087720
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KEYWORD
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nonn
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AUTHOR
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John W. Layman (layman(AT)math.vt.edu), Sep 29 2003
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