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A166362 a(n) = phi(nonprime(n)). 1
1, 2, 2, 4, 6, 4, 4, 6, 8, 8, 6, 8, 12, 10, 8, 20, 12, 18, 12, 8, 16, 20, 16, 24, 12, 18, 24, 16, 12, 20, 24, 22, 16, 42, 20, 32, 24, 18, 40, 24, 36, 28, 16, 30, 36, 32, 48, 20, 32, 44, 24, 24, 36, 40, 36, 60, 24, 32, 54, 40, 24, 64, 42, 56, 40, 24, 72, 44, 60, 46, 72, 32, 42, 60 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Here 1, 4, 6, 8, 9, 10, 12, 14, 15, 16,.. are the nonprimes A018252. Or, unit together with EulerPhi of n-th composite number (i.e. A073256).

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..10000

MATHEMATICA

Table[EulerPhi[FixedPoint[n + PrimePi@# &, n + PrimePi@n]], {n, 1, 100}] (* G. C. Greubel, May 10 2016 *)

CROSSREFS

Cf. A000010, A073256, A018252.

Sequence in context: A286542 A278973 A073256 * A050469 A085730 A232065

Adjacent sequences:  A166359 A166360 A166361 * A166363 A166364 A166365

KEYWORD

nonn,look

AUTHOR

Juri-Stepan Gerasimov, Oct 12 2009

EXTENSIONS

Entries checked by R. J. Mathar, May 21 2010

STATUS

approved

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Last modified March 18 17:51 EDT 2019. Contains 321292 sequences. (Running on oeis4.)