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A165978
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Largest prime factor of number formed from a(n-1) with a 1 added at the end, a(1)=2.
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1
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2, 7, 71, 79, 113, 29, 97, 971, 83, 277, 163, 233, 37, 53, 59, 197, 73, 43, 431, 479, 1597, 15971, 383, 1277, 43, 431, 479, 1597, 15971, 383, 1277, 43, 431, 479, 1597, 15971, 383, 1277, 43, 431, 479, 1597, 15971, 383, 1277, 43, 431, 479, 1597, 15971, 383, 1277
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OFFSET
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1,1
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COMMENTS
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Conjecture: The same number will never occur twice in this sequence. - Lowell
Disproved - cycle 43,431,479,1597,15971,383,1277 repeats starting at a(18). - Chandler
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LINKS
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EXAMPLE
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Largest prime factor of 21 is 7, so next term after 2 is 7.
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MATHEMATICA
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NestList[FactorInteger[10#+1][[-1, 1]]&, 2, 60] (* Harvey P. Dale, Nov 10 2020 *)
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CROSSREFS
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KEYWORD
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base,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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