

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
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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



