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Search: id:A136166
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| A136166 |
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a(n) = the number of divisors of n that are each not coprime to the previous or the following divisor of n. |
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+0
6
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| 0, 0, 0, 2, 0, 2, 0, 3, 2, 2, 0, 3, 0, 2, 2, 4, 0, 4, 0, 5, 2, 2, 0, 5, 2, 2, 3, 5, 0, 4, 0, 5, 2, 2, 2, 6, 0, 2, 2, 6, 0, 6, 0, 5, 3, 2, 0, 7, 2, 4, 2, 5, 0, 6, 2, 6, 2, 2, 0, 7, 0, 2, 3, 6, 2, 6, 0, 5, 2, 4, 0, 9, 0, 2, 4, 5, 2, 6, 0, 8, 4, 2, 0, 8, 2, 2, 2, 7, 0, 8, 2, 5, 2, 2, 2, 9, 0, 4, 5, 8, 0, 6, 0, 7, 4
(list; graph; listen)
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OFFSET
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1,4
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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) =5 divisors that are each next to at least one divisor they are not coprime to. (These five divisors are 2,4,7,14,28.)
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CROSSREFS
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Cf. A136164, A136165, A136167.
Adjacent sequences: A136163 A136164 A136165 this_sequence A136167 A136168 A136169
Sequence in context: A029188 A090290 A144494 this_sequence A046522 A112631 A096500
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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 13 2008
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