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A078557
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Squarefree balanced numbers (i.e. squarefree members of A020492).
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2
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1, 2, 3, 6, 14, 15, 30, 35, 42, 70, 78, 105, 190, 210, 357, 418, 570, 714, 910, 1045, 1254, 2090, 2730, 3135, 4522, 4674, 5278, 6270, 10659, 12441, 13566, 14630, 15834, 16770, 20026, 21318, 23374, 24871, 24882, 24969, 25070, 25714, 27170, 29029
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refs;
listen;
history;
text;
internal format)
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OFFSET
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1,2
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LINKS
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Donovan Johnson, Table of n, a(n) for n = 1..10000
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EXAMPLE
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210 = 2*3*5*7, sigma(210) = 576, phi(210) = 48, 576/48 = 12.
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MATHEMATICA
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Do[s=DivisorSigma[1, n]/EulerPhi[n]; If[IntegerQ[s]&&!Equal[MoebiusMu[n], 0], k=k+1; Print[n]], {n, 1, 2100000}]
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CROSSREFS
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Cf. A020492.
Sequence in context: A122839 A121556 A123041 * A005537 A193093 A182756
Adjacent sequences: A078554 A078555 A078556 * A078558 A078559 A078560
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Dec 06 2002
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STATUS
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approved
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