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Search: id:A159836
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| A159836 |
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Integers n such that the orbit n, f(n), f(f(n)), ... is eventualy periodic with period 2, where f(n)=Product[a(k)^p(k)] when n has the prime factorization n=Product[p(k)^a(k)]. |
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+0
1
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| 8, 9, 18, 24, 25, 32, 36, 40, 45, 49, 50, 56, 63, 64, 75, 81, 88, 90, 96, 98, 99, 100, 104, 117, 120, 121, 125, 126, 128, 136, 144, 147, 150, 152, 153, 160, 162, 168, 169, 171, 175, 180, 184, 192, 196, 198, 200
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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It is proved in the reference that for every positive integer n the orbit n, f(n), f(f(n)), ... is eventually periodic with period 1 or 2.
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REFERENCES
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Problem 11315, American Mathematical Monthly, May 2009, page 470.
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CROSSREFS
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A008477, A008478
Sequence in context: A057104 A095191 A050706 this_sequence A069809 A067544 A022313
Adjacent sequences: A159833 A159834 A159835 this_sequence A159837 A159838 A159839
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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), Apr 23 2009
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