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A317272
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Numbers k such that Phi(k,x) is a cyclotomic polynomial with middle coefficient different from -1, 0, 1.
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1
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385, 770, 1155, 1365, 1540, 1925, 2065, 2145, 2310, 2415, 2465, 2695, 2717, 2730, 2737, 2821, 2849, 3003, 3080, 3255, 3315, 3465, 3619, 3850, 4095, 4130, 4199, 4235, 4277, 4290, 4543, 4620, 4785, 4830, 4845, 4879, 4930, 4991
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OFFSET
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1,1
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COMMENTS
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LINKS
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EXAMPLE
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385 is the first item in the list because Phi(385,x) is the first cyclotomic polynomial with middle coefficient different from -1,0,1 (the middle term is -3x^120)
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MAPLE
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filter:= proc(n) local p, d;
p:= numtheory:-cyclotomic(n, x);
d:= degree(p, x);
abs(coeff(p, x, d/2))>1
end proc:
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MATHEMATICA
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Select[Range[3, 4000],
Abs[Coefficient[Cyclotomic[#, x], x, EulerPhi[#]/2]] > 1 &]
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PROG
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(PARI) isok(n) = (n > 2) && (abs(polcoeff(polcyclo(n), eulerphi(n)/2)) > 1); \\ Michel Marcus, Aug 02 2018
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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