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Search: id:A097000
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| A097000 |
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A062401(x)=phi[sigma(x)] function is iterated; initial value=2^n; a(n)=smallest term of trajectory. |
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+0
1
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| 2, 4, 8, 16, 32, 64, 128, 256, 432, 1024, 1728, 4096, 1800, 7200, 32768, 65536, 131072, 262144, 326592, 1036800, 1658880, 4194304, 4838400, 16777216, 33554432, 67108864, 82301184, 207360000, 361267200, 414720000
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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n=8: 2^n=256, list={256,432,480,432,...}, max=a(8)=256, the start value;
n=13:2^n=8192,list={8192,10584,8640,8064,6144,3456,[2560,1800,2880, 3024,3840,3456],2560,..}, min=1800=a(13), a term of 6-cycle.
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MATHEMATICA
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fs[x_] :=EulerPhi[DivisorSigma[1, x]] itef[x_, hos_] :=NestList[fs, x, hos] Table[Min[itef[2^w, 200]], {w, 1, 30}]
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CROSSREFS
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Cf. A000010, A000203, A062401, A096852.
Sequence in context: A079262 A087079 A009694 this_sequence A054046 A008861 A145115
Adjacent sequences: A096997 A096998 A096999 this_sequence A097001 A097002 A097003
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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), Jul 21 2004
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