A096999 A062401(x)=phi[sigma(x)] function is iterated; initial value=2^n; a(n)=largest term of trajectory.

2, 6, 8, 30, 96, 126, 128, 480, 600, 3840, 2048, 8190, 10584, 27000, 32768, 196560, 311040, 851840, 1161216, 2250600, 2640704, 150992640, 150992640, 283740364800, 283740364800, 283740364800, 283740364800, 7608287232, 7608287232

Offset

1,1

Links

Table of n, a(n) for n=1..29.

Example

n=8: 2^n=256, list={256,432,480,432,...}, max=a(8)=480

Mathematica

fs[x_] :=EulerPhi[DivisorSigma[1, x]] itef[x_, hos_] :=NestList[fs, x, hos] Table[Max[itef[2^w, 200]], {w, 1, 30}]

Crossrefs

Cf. A000010, A000203, A062401, A096852.

Sequence in context: A086323 A336618 A075999 * A019199 A094678 A076507

Adjacent sequences: A096996 A096997 A096998 * A097000 A097001 A097002

Keyword

nonn

Author

Labos Elemer, Jul 21 2004

Status

approved