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Search: id:A047830
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| A047830 |
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Least number which becomes prime after exactly n iterations of f(x) = sum of prime factors of x. |
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+0
1
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| 2, 4, 14, 26, 62, 134, 393, 1774, 13682, 41037, 167073, 334142, 4677862, 14033577, 79464886, 476789307
(list; graph; listen)
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OFFSET
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0,1
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COMMENT
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f(x) = sum of prime factors without multiplicity, so that f(1500) = 2+3+5 = 10.
a(16) > 10^9. [From Donovan Johnson (donovan.johnson(AT)yahoo.com), Oct 13 2009]
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CROSSREFS
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Sequence in context: A102930 A135113 A050564 this_sequence A036051 A115626 A116021
Adjacent sequences: A047827 A047828 A047829 this_sequence A047831 A047832 A047833
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KEYWORD
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nonn
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AUTHOR
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David W. Wilson (davidwwilson(AT)comcast.net)
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EXTENSIONS
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a(14)-a(15) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Oct 13 2009
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