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Search: id:A109840
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| A109840 |
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Largest prime factor of the reverse concatenation of the first n consecutive odd numbers. |
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+0
1
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| 31, 59, 443, 13933, 2609, 83089, 18937669, 57697, 71615663503, 161768817795401, 4356390089, 4668342004597, 109230695824219, 2770122504473483, 217596035578054625221, 1721572826917, 659160492491
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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n = 6: a(6) = 83089 because 131197531 = 1579 * 83089.
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MATHEMATICA
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s=1; ss={}; Do[news=FromDigits[Flatten[{IntegerDigits[n], IntegerDigits[s]}]]; fi=FactorInteger[news][[ -1, 1]]; s=news; AppendTo[ss, fi], {n, 3, 60, 2}]; A109840=ss
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CROSSREFS
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Cf. A109837 = smallest prime factor of the reverse concatenation of the first n consecutive odd numbers.
Sequence in context: A043953 A139954 A153636 this_sequence A108293 A063339 A115833
Adjacent sequences: A109837 A109838 A109839 this_sequence A109841 A109842 A109843
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KEYWORD
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base,nonn
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AUTHOR
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Zak Seidov (zakseidov(AT)yahoo.com), Jul 05 2005
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