A077083 - OEIS

A077083

Length of iteration until fixed point is reached when Phi[Sigma[n]+phi(n)]=A077080 is iterated with initial value of n.

1, 1, 2, 2, 3, 1, 2, 16, 16, 1, 2, 16, 17, 17, 16, 15, 16, 15, 16, 1, 2, 1, 2, 14, 14, 16, 15, 14, 15, 14, 15, 13, 14, 15, 15, 10, 11, 15, 14, 13, 14, 11, 12, 2, 14, 1, 2, 1, 12, 6, 2, 12, 13, 3, 2, 2, 3, 1, 2, 11, 12, 11, 2, 11, 14, 10, 11, 13, 2, 2, 3, 5, 6, 14, 10, 10, 2, 12, 13, 9

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OFFSET

1,3

LINKS

Table of n, a(n) for n=1..80.

FORMULA

a(n)=Length[FixedPointList[A077080, n]]-1.

EXAMPLE

n=1,2,6,10,..864: a[n]=1, n is fixed point for some n; n=225: results in iteration sequence of 44 terms: {225,522,444,...,471744,653312,570240}, 44=a[225].

MATHEMATICA

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

CROSSREFS

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

Sequence in context: A354584 A088598 A200751 * A274528 A166248 A180257

Adjacent sequences: A077080 A077081 A077082 * A077084 A077085 A077086

KEYWORD

nonn

AUTHOR

Labos Elemer, Oct 28 2002

STATUS

approved