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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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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; refs; listen; history; internal format)
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OFFSET
| 1,4
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LINKS
| Diana Mecum, Table of n, a(n) for n = 1..1000
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EXAMPLE
| 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
| Cf. A136164, A136165, A136167.
Sequence in context: A153585 A169611 A144494 * A046522 A112631 A158706
Adjacent sequences: A136163 A136164 A136165 * A136167 A136168 A136169
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KEYWORD
| nonn
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AUTHOR
| Leroy Quet, Dec 17 2007
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EXTENSIONS
| More terms from Diana Mecum (diana.mecum(AT)gmail.com), Jul 13 2008
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