login
A062402(x)=sigma(phi[x]) function is iterated; initial value=2^n; a(n)=largest term of trajectory.
0

%I #4 Oct 15 2013 22:32:33

%S 2,4,12,16,72,252,312,256,1512,1860,12264,6552,26208,34200,93600,

%T 65536,833280,1116024,2239920,4464096,9865440,8124480,569540160,

%U 569540160,1100946774480,1100946774480,1100946774480,1100946774480,34696672920

%N A062402(x)=sigma(phi[x]) function is iterated; initial value=2^n; a(n)=largest term of trajectory.

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

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

%Y Cf. A000010, A000203, A062402, A096852.

%K nonn

%O 1,1

%A _Labos Elemer_, Jul 21 2004