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A136165 a(n) = the number of divisors of n that are each not noncoprime to either the previous or the following divisor of n. 6
1, 2, 2, 1, 2, 2, 2, 1, 1, 2, 2, 3, 2, 2, 2, 1, 2, 2, 2, 1, 2, 2, 2, 3, 1, 2, 1, 1, 2, 4, 2, 1, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 1, 3, 2, 2, 3, 1, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 5, 2, 2, 3, 1, 2, 2, 2, 1, 2, 4, 2, 3, 2, 2, 2, 1, 2, 2, 2, 2, 1, 2, 2, 4, 2, 2, 2, 1, 2, 4, 2, 1, 2, 2, 2, 3, 2, 2, 1, 1, 2, 2, 2, 1, 4 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Diana Mecum, Table of n, a(n) for n = 1..1000

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. But 2 and 4 are adjacent divisors which are not coprime. And 7 is next to 14 among divisors of 28 and 7 and 14 are not coprime. Therefore there is a(28) = 1 divisor (1) that is not next to another divisor that it is not coprime to.

CROSSREFS

Cf. A136164, A136166, A136167.

Sequence in context: A230594 A072463 A128853 * A134193 A230259 A085030

Adjacent sequences:  A136162 A136163 A136164 * A136166 A136167 A136168

KEYWORD

nonn

AUTHOR

Leroy Quet, Dec 17 2007

EXTENSIONS

More terms from Diana L. Mecum, Jul 11 2007

STATUS

approved

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Last modified September 27 12:30 EDT 2020. Contains 337380 sequences. (Running on oeis4.)