A097001 A062402(x)=sigma(phi[x]) function is iterated; initial value=2^n; a(n)=largest term of trajectory.

2, 4, 12, 16, 72, 252, 312, 256, 1512, 1860, 12264, 6552, 26208, 34200, 93600, 65536, 833280, 1116024, 2239920, 4464096, 9865440, 8124480, 569540160, 569540160, 1100946774480, 1100946774480, 1100946774480, 1100946774480, 34696672920

Offset: 1

Author

Labos Elemer, Jul 21 2004

Keywords

• nonn

Examples

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

Crossrefs

Cf. A000010, A000203, A062402, A096852.

Programs

Mathematica

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