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A086761
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Numbers n such that n-th cyclotomic polynomial has exactly 5 nonzero terms.
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2
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5, 10, 20, 25, 40, 50, 80, 100, 125, 160, 200, 250, 320, 400, 500, 625, 640, 800, 1000, 1250, 1280, 1600, 2000, 2500, 2560, 3125, 3200, 4000, 5000, 5120, 6250, 6400, 8000, 10000, 10240, 12500, 12800, 15625, 16000, 20000, 20480, 25000, 25600, 31250, 32000
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OFFSET
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1,1
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COMMENTS
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A206787(a(n)) = 6. [Reinhard Zumkeller, Feb 12 2012]
All terms have the form 2^a 5^b with a >= 0 and b > 0. - T. D. Noe, Feb 13 2012
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LINKS
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Table of n, a(n) for n=1..45.
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MATHEMATICA
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Select[Range[1000], Count[CoefficientList[Cyclotomic[#, x], x], 0] == EulerPhi[#] - 4 &] (* T. D. Noe, Feb 13 2012 *)
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CROSSREFS
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Cf. A051664, A065119.
Sequence in context: A062052 A115799 A072703 * A045191 A065958 A065969
Adjacent sequences: A086758 A086759 A086760 * A086762 A086763 A086764
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KEYWORD
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nonn
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AUTHOR
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Yuval Dekel (dekelyuval(AT)hotmail.com), Aug 02 2003
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EXTENSIONS
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More terms from T. D. Noe, Feb 13 2012
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STATUS
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approved
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