A136165 - OEIS

%I #8 Apr 09 2014 10:17:01

%S 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,

%T 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,

%U 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

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

%H Diana Mecum, <a href="/A136165/b136165.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. 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.

%Y Cf. A136164, A136166, A136167.

%K nonn

%O 1,2

%A _Leroy Quet_, Dec 17 2007

%E More terms from _Diana L. Mecum_, Jul 11 2007