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A049113
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Number of powers of 2 in sequence obtained when EulerPhi(A000010) is repeatedly applied to n.
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2
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1, 2, 2, 3, 3, 2, 2, 4, 2, 3, 3, 3, 3, 2, 4, 5, 5, 2, 2, 4, 3, 3, 3, 4, 4, 3, 2, 3, 3, 4, 4, 6, 4, 5, 4, 3, 3, 2, 4, 5, 5, 3, 3, 4, 4, 3, 3, 5, 3, 4, 6, 4, 4, 2, 5, 4, 3, 3, 3, 5, 5, 4, 3, 7, 5, 4, 4, 6, 4, 4, 4, 4, 4, 3, 5, 3, 5, 4, 4, 6, 2, 5, 5, 4, 7, 3, 4, 5, 5, 4, 4, 4, 5, 3, 4, 6, 6, 3, 5, 5, 5, 6, 6, 5, 5
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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EXAMPLE
| If n=164, the "iterated Phi-sequence" for n is {164,80,32,16,8,4,2,1}. It includes 6 powers of 2 at the end, so a(164)=6.
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MATHEMATICA
| pwrs2 = NestList[2#&, 1, 15];
Table[Length[Intersection[NestWhileList[EulerPhi[#]&, i, # > 1 &], pwrs2]], {i, 100}] (* Harvey P. Dale, Dec 12 2010 *)
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CROSSREFS
| A000010.
Sequence in context: A059906 A112046 A076902 * A055093 A196058 A081844
Adjacent sequences: A049110 A049111 A049112 * A049114 A049115 A049116
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu)
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