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%I #48 Apr 29 2018 12:21:39
%S 105,165,195,210,255,273,285,315,330,345,357,385,390,420,429,455,495,
%T 510,525,546,555,561,570,585,595,609,615,627,630,645,660,665,690,705,
%U 714,715,735,759,765,770,777,780,795,805,819,825,840,855
%N Numbers k such that Phi(k,x) is a cyclotomic polynomial containing a coefficient with an absolute value greater than one.
%C Previous name was: Orders of cyclotomic polynomials containing a coefficient with an absolute value greater than one.
%C First occurrence of A137979(n)=k is given in A013594.
%C From _David A. Corneth_, Apr 21 2018: (Start)
%C Terms are composite.
%C If k is a term of the sequence then so is k * m for m > 0.
%C Let a primitive term p of this sequence be a term of which no divisor is in the sequence. Then p is an odd squarefree number. (End)
%H Robert G. Wilson v, <a href="/A013590/b013590.txt">Table of n, a(n) for n = 1..1627</a>
%p isA013590 := proc(n)
%p numtheory[cyclotomic](n,x) ;
%p {coeffs(%,x)} ;
%p map(abs,%) ;
%p if % minus {1} = {} then
%p false;
%p else
%p true;
%p end if;
%p end proc:
%p for n from 1 do
%p if isA013590(n) then
%p print(n);
%p end if;
%p end do: # _R. J. Mathar_, Nov 28 2016
%t S[ n_ ] := For[ j=1; t=0, j<n, j++, t=Cases[ CoefficientList[ Cyclotomic[ j, x ], x ], k_ /; Abs[ k ]>1 ]; If[ Length[ t ]!=0, Print[ j ] ] ]; S[ 856 ]
%t f[n_] := Max@ Abs@ CoefficientList[ Cyclotomic[n, x], x]; Select[ Range@ 1000, f@# > 1 &] (* _Robert G. Wilson v_ *)
%t Select[Range[900],Max[Abs[CoefficientList[Cyclotomic[#,x],x]]]>1&] (* _Harvey P. Dale_, Mar 13 2013 *)
%o (PARI) is(n)=for(k=0,n,if(abs(polcoeff(polcyclo(n),k))>1,return(n)));0
%o for(n=1,1000,if(is(n),print1(n,", "))) \\ _Derek Orr_, Apr 22 2015
%Y Cf. A013594, A117223, A117318, A137979.
%Y Flat cyclotomic polynomial: A117223 (order 3), A117318 (order 4).
%K nonn
%O 1,1
%A Peter T. Wang (peterw(AT)cco.caltech.edu)
%E Definition clarified by _Harvey P. Dale_, Mar 13 2013
%E New name from _Michel Marcus_, Apr 29 2018
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