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Search: id:A136164
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| A136164 |
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a(n) = the number of divisors of n that are each coprime to the previous or the following divisor of n. |
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+0
6
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| 0, 2, 2, 2, 2, 3, 2, 2, 2, 3, 2, 4, 2, 3, 3, 2, 2, 3, 2, 4, 3, 3, 2, 4, 2, 3, 2, 4, 2, 5, 2, 2, 3, 3, 3, 4, 2, 3, 3, 5, 2, 5, 2, 4, 4, 3, 2, 4, 2, 3, 3, 4, 2, 3, 3, 5, 3, 3, 2, 6, 2, 3, 4, 2, 3, 5, 2, 4, 3, 5, 2, 6, 2, 3, 3, 4, 3, 5, 2, 5, 2, 3, 2, 7, 3, 3, 3, 4, 2, 7, 3, 4, 3, 3, 3, 4, 2, 3, 4, 4, 2, 5, 2, 4, 5
(list; graph; listen)
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OFFSET
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1,2
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LINKS
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Diana Mecum, Table of n, a(n) for n = 1..1000
Leroy Quet, Home Page (listed in lieu of email address)
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EXAMPLE
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The divisors of 28 are 1,2,4,7,14,28. Among adjacent pairs of divisors, 1 and 2 are coprime, and 4 and 7 are coprime. Therefore there are a(28) = 4 divisors (1,2,4,7) that are each next to another divisor that they are coprime to.
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CROSSREFS
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Cf. A136165, A136166, A136167.
Adjacent sequences: A136161 A136162 A136163 this_sequence A136165 A136166 A136167
Sequence in context: A105561 A087133 A062843 this_sequence A033947 A069719 A074592
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet Dec 17 2007
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EXTENSIONS
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More terms from Diana Mecum (diana.mecum(AT)gmail.com), Jul 11 2007, Jul 13 2008
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