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%I #11 Nov 11 2018 15:03:10
%S 7735,11305,13845,17255,20615,21945,22015,23919,25935,26565,28595,
%T 31535,33495,33915,35105,35805,36465,39767,39865,40755,41041,41055,
%U 42315,42665,42735,45885,46189,46655,47355,47957,49665,50505,51051,51765
%N Odd squarefree numbers n such that the cyclotomic polynomial Phi(n,x) is not coefficient convex.
%C Gallot and Moree say that a cyclotomic polynomial is coefficient convex if the union of the coefficients is a range of consecutive integers. They prove that if n is ternary (the product of three distinct odd primes), then Phi(n,x) is coefficient convex. All numbers in this sequence have more than three odd prime factors.
%H T. D. Noe, <a href="/A146960/b146960.txt">Table of n, a(n) for n = 1..1000</a>
%H Yves Gallot and Pieter Moree, <a href="http://arxiv.org/abs/0810.5496">Neighboring ternary cyclotomic coefficients differ by at most one</a>, arXiv:0810.5496 [math.NT], 2008.
%t nn = Select[Range[1155, 59999, 2], SquareFreeQ[#] && PrimeNu[#] > 3&];
%t Reap[For[k = 1, k <= Length[nn], k++, n = nn[[k]]; If[{1} != (CoefficientList[Cyclotomic[n, x], x] // Union // Differences // Union), Print[n]; Sow[n]]]][[2, 1]] (* _Jean-François Alcover_, Nov 11 2018 *)
%Y Subsequence of A056911 (odd squarefree numbers).
%K nonn
%O 1,1
%A _T. D. Noe_, Nov 03 2008
%E Definition corrected by _T. D. Noe_, Nov 16 2008
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