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

1,2

Links

Table of n, a(n) for n=1..49.

Formula

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

Example

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

Mathematica

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

Crossrefs

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

Sequence in context: A274213 A350315 A078706 * A333936 A193896 A099162

Adjacent sequences: A077079 A077080 A077081 * A077083 A077084 A077085

Keyword

nonn

Author

Labos Elemer, Oct 28 2002

Status

approved