A077082 Largest value arising when phi(sigma(n)+phi(n))=A077080 is iterated with initial value of n.

1, 2, 3, 6, 6, 6, 7, 1044, 1044, 10, 11, 1044, 1044, 1044, 1044, 1044, 1044, 1044, 1044, 20, 21, 22, 23, 1044, 1044, 1044, 1044, 1044, 1044, 1044, 1044, 1044, 1044, 1044, 1044, 1044, 1044, 1044, 1044, 1044, 1044, 1044, 1044, 48, 1044, 46, 47, 48, 1044

Offset: 1

Author

Labos Elemer, Oct 28 2002

Keywords

• nonn

Examples

			n=225: results in iteration sequence of 44 terms: {225,522,444,...,471744,653312,570240}, largest is 653312=a(225).
		

Crossrefs

Cf. A000010, A000203, A065387, A077080-A077085.

Programs

Mathematica

f[x_] := EulerPhi[DivisorSigma[1, x]+EulerPhi[x]] Table[Max[FixedPointList[f, w]], {w, 1, 1024}]

Formula

a(n) = Max[FixedPointList[A077080, n]]. See program below. Seems convergent. [tested for initial values below 1024.]