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A097002 A062402(x)=sigma(phi[x]) function is iterated; initial value=2^n; a(n)=smallest term of trajectory. 0
1, 3, 7, 15, 31, 63, 127, 255, 511, 1023, 2047, 4095, 8191, 6045, 24552, 65535, 131071, 262143, 524287, 1048575, 2097151, 4194303, 8388607, 16777215, 33554431, 67108863, 134217727, 268435455, 536870911, 1073741823 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..30.

EXAMPLE

n=13: 2^n=8192, trajectory ={8192, 8191, 26208, [20440], 20440, .. a[13]=8191 arose in transient.

MATHEMATICA

gf[x_] :=DivisorSigma[1, EulerPhi[x]] gite[x_, hos_] :=NestList[gf, x, hos] Table[Min[gite[2^w, 200]], {w, 1, 30}]

CROSSREFS

Cf. A000010, A000203, A062402, A096857.

Sequence in context: A105755 A043764 A213248 * A060152 A126646 A000225

Adjacent sequences:  A096999 A097000 A097001 * A097003 A097004 A097005

KEYWORD

nonn

AUTHOR

Labos Elemer, Jul 21 2004

STATUS

approved

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Last modified April 20 05:52 EDT 2014. Contains 240779 sequences.