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A136167 a(n) = the number of divisors of n that are each not coprime to any adjacent (previous or following) divisor of n. 6
1, 0, 0, 1, 0, 1, 0, 2, 1, 1, 0, 2, 0, 1, 1, 3, 0, 3, 0, 2, 1, 1, 0, 4, 1, 1, 2, 2, 0, 3, 0, 4, 1, 1, 1, 5, 0, 1, 1, 3, 0, 3, 0, 2, 2, 1, 0, 6, 1, 3, 1, 2, 0, 5, 1, 3, 1, 1, 0, 6, 0, 1, 2, 5, 1, 3, 0, 2, 1, 3, 0, 6, 0, 1, 3, 2, 1, 3, 0, 5, 3, 1, 0, 5, 1, 1, 1, 4, 0, 5, 1, 2, 1, 1, 1, 8, 0, 3, 2, 5, 0, 3, 0, 4, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,8

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. Therefore there are a(28) =2 divisors that are each not next to any divisor they are coprime to. (These two divisors are 14 and 28.)

CROSSREFS

Cf. A136164, A136165, A136166.

Sequence in context: A308427 A252736 A253559 * A140748 A185305 A259875

Adjacent sequences:  A136164 A136165 A136166 * A136168 A136169 A136170

KEYWORD

nonn

AUTHOR

Leroy Quet, Dec 17 2007

EXTENSIONS

More terms from Diana L. Mecum, Jul 13 2008

STATUS

approved

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Last modified May 18 04:22 EDT 2021. Contains 343994 sequences. (Running on oeis4.)