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Search: id:A057237
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| A057237 |
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Maximum k <= n such that 1, 2, ..., k are all relatively prime to n. |
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+0
7
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| 1, 1, 2, 1, 4, 1, 6, 1, 2, 1, 10, 1, 12, 1, 2, 1, 16, 1, 18, 1, 2, 1, 22, 1, 4, 1, 2, 1, 28, 1, 30, 1, 2, 1, 4, 1, 36, 1, 2, 1, 40, 1, 42, 1, 2, 1, 46, 1, 6, 1, 2, 1, 52, 1, 4, 1, 2, 1, 58, 1, 60, 1, 2, 1, 4, 1, 66, 1, 2, 1, 70, 1, 72, 1, 2, 1, 6, 1, 78, 1, 2, 1, 82, 1, 4, 1, 2, 1, 88, 1, 6, 1, 2, 1
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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In reduced residue system for n [=RRS(n)] the [initial] segment of consecutive integers, i.e. of which no number is missing is {1,2,....,a[n]}. The first missing term from RRS(n) is 1+a(n), the least prime divisor.. E.g. n=121 : RRS[121] = {1,2,3,4,5,6,7,8,9,10,lag,12,..}, i.e. no 11 is in RRS; a[n] is the length of longest lag-free number segment consisting of consecutive integers, since A020639[n] divides n. - Labos E. (labos(AT)ana.sote.hu), May 14 2003
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LINKS
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Leroy Quet, Home Page (listed in lieu of email address)
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FORMULA
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For n >= 2, a(n) = (smallest prime dividing n) - 1
For n >= 2, a(n) = (n-1) mod (smallest prime dividing n); cf. A083218. - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Apr 22 2003
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EXAMPLE
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a(25) = 4 because 1, 2, 3 and 4 are relatively prime to 25.
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CROSSREFS
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Cf. A020639, A083218.
Cf. A066169.
Sequence in context: A018783 A114326 A060680 this_sequence A049559 A063994 A076512
Adjacent sequences: A057234 A057235 A057236 this_sequence A057238 A057239 A057240
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet Sep 20 2000
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