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A098202 a(n) is the length of the iteration trajectory when the cototient function (A051953) is applied to the n-th primorial number (A002110(n)). 2
3, 5, 8, 12, 18, 20, 31, 32, 41, 43, 61, 65, 80, 77, 95, 125, 131, 125, 157, 173, 140, 192, 195, 221, 213, 212, 261, 269, 277, 300, 296, 321, 336, 329, 358, 367 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..36.

FORMULA

a(n) = A053475(A002110(n)). - Robert G. Wilson v, Sep 22 2004

EXAMPLE

n=3: list={30,22,12,8,4,2,1,0}, a(4)=8.

MATHEMATICA

g[x_] := x - EulerPhi[x]; f[x_] := Length[ FixedPointList[g, x]] - 1; q[x_] := Product[ Prime[j], {j, x}]; Table[ f[ q[n]], {n, 33}]

CROSSREFS

Cf. A051953, A053475, A002110.

Sequence in context: A265061 A265062 A265063 * A164653 A001973 A248374

Adjacent sequences:  A098199 A098200 A098201 * A098203 A098204 A098205

KEYWORD

nonn

AUTHOR

Labos Elemer, Sep 22 2004

EXTENSIONS

More terms from Robert G. Wilson v, Sep 22 2004

STATUS

approved

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Last modified May 30 05:35 EDT 2020. Contains 334712 sequences. (Running on oeis4.)