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Search: id:A077092
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| 0, 4, 24, 8064, 34944, 35520, 38880, 69480, 268850, 420096
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OFFSET
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1,2
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COMMENT
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When iteration of f[]=Phi[Sigma[]-Phi[]] is started at various initial values, not ending in cycles and converging, it ends at these fixed points.
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EXAMPLE
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n=30: FixedPointList={30,32,46,20,16,22,12,8,10,6,4},end=4; n=94: FixedPointList={94,42,24},end=24. n=41708: FixedPointList={41708,26064,32352,21216,15232,8064},end=8064; n=12100: FixedPointList={12100,24000,34944},end=34944.
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MATHEMATICA
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f[x_] := EulerPhi[DivisorSigma[1, x]-EulerPhi[x]] Do[s=NestList[f, n, 100]; s1=Part[s, 99]; s2=Part[s, 100]; If[Equal[s1, s2]&&!PrimeQ[n], Print[{n, s1}]], {n, 1, 1000}]
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CROSSREFS
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Cf. A077090-A077100.
Sequence in context: A110972 A065711 A077093 this_sequence A092435 A058230 A103644
Adjacent sequences: A077089 A077090 A077091 this_sequence A077093 A077094 A077095
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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), Oct 31 2002
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