A134518 - OEIS

%I #7 Jan 25 2016 21:17:45

%S 105,385,2431,2717,8671,17119,19499,20213,20213,34891,34891,93439,

%T 93439,93439,93439,93439,282367,282367,282367,282367,282367,282367,

%U 282367,282367,282367,617927,617927,849647,849647,849647,849647,849647,874507

%N Least k such that the cyclotomic polynomial Phi(k,x) contains n or -n as a coefficient, where k is restricted to be the product of 3 distinct prime numbers.

%C It is well-known that k=105 is the first number for which Phi(k,x) has a coefficient other than -1, 0, or 1. See A013594 for the case when k has no restrictions.

%H Jia Zhao and Xianke Zhang, <a href="http://dx.doi.org/10.1016/j.jnt.2010.03.012">Coefficients of ternary cyclotomic polynomials</a>, Journal of Number Theory, Volume 130, Issue 10, October 2010, Pages 2223-2237.

%Y Cf. A007304, A013594.

%K nonn

%O 2,1

%A _T. D. Noe_, Oct 29 2007