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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

%I

%S 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,

%T 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,

%U 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

%N a(n) = the number of divisors of n that are each not coprime to any adjacent (previous or following) divisor of n.

%H Diana Mecum, <a href="/A136167/b136167.txt">Table of n, a(n) for n = 1..1000</a>

%e 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.)

%Y Cf. A136164, A136165, A136166.

%K nonn

%O 1,8

%A _Leroy Quet_, Dec 17 2007

%E More terms from _Diana L. Mecum_, Jul 13 2008

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Last modified June 12 09:24 EDT 2021. Contains 344946 sequences. (Running on oeis4.)