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Search: id:A081373
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| 1, 2, 1, 2, 1, 3, 1, 2, 2, 3, 1, 4, 1, 3, 1, 2, 1, 4, 1, 3, 2, 2, 1, 4, 1, 3, 2, 4, 1, 5, 1, 2, 2, 3, 1, 5, 1, 3, 2, 4, 1, 6, 1, 3, 3, 2, 1, 5, 2, 4, 1, 4, 1, 4, 2, 5, 2, 2, 1, 6, 1, 2, 3, 2, 1, 5, 1, 3, 1, 6, 1, 7, 1, 4, 3, 5, 2, 8, 1, 4, 1, 4, 1, 9, 1, 3, 1, 5, 1, 10, 2, 2, 3, 2, 3, 5, 1, 4, 4, 6
(list; graph; listen)
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OFFSET
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1,2
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EXAMPLE
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n=16: phi(k)={1,1,2,2,4,2,6,4,6,4,10,4,12,6,8,8} for k=1,..,n; 2 numbers exist with phi[x]==8,{16,15} so a(16)=2; if n=p odd prime number, then a(p)=1 with phi[k]=p-1.
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MATHEMATICA
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f[x_] := Count[Table[EulerPhi[j]-EulerPhi[x], {j, 1, x}], 0] Table[f[w], {w, 1, 100}]
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CROSSREFS
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Cf. A000010, A067004.
Adjacent sequences: A081370 A081371 A081372 this_sequence A081374 A081375 A081376
Sequence in context: A136107 A124768 A072527 this_sequence A029436 A060135 A057112
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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), Mar 24 2003
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