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A145190
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Numbers n such that phi(1)*phi(2)*...*phi(n) / n is an integer, where phi(i) is the totient function (A000010).
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0
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1, 4, 8, 9, 12, 15, 16, 18, 20, 24, 25, 27, 30, 32, 33, 35, 36, 40, 42, 44, 45, 48, 49, 50, 54, 55, 56, 60, 63, 64, 65, 66, 69, 70, 72, 75, 77, 78, 80, 81, 84, 87, 88, 90, 91, 92, 96, 98, 99, 100, 104, 105, 108, 110, 112, 115, 116, 117, 119, 120, 121, 123
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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MATHEMATICA
| Select[Range[200], IntegerQ[Product[EulerPhi[i], {i, 1, #}]/#] &] (* Carl Najafi, Aug 19 2011 *)
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CROSSREFS
| Cf. A048290, A000010, A144857
Sequence in context: A078136 A037973 A044844 * A177713 A004753 A144794
Adjacent sequences: A145187 A145188 A145189 * A145191 A145192 A145193
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KEYWORD
| easy,nonn
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AUTHOR
| Ctibor O. Zizka (c.zizka(AT)email.cz), Oct 03 2008
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EXTENSIONS
| More terms from Carl Najafi (carlnajafi(AT)gmail.com), Aug 19 2011
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