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A117483 Numbers k for which pi(phi(k)) equals phi(pi(k)). 0
0, 1, 3, 4, 5, 8, 10, 11, 17, 20, 22, 30, 31, 41, 50, 59, 67, 75, 83, 109, 127, 157, 174, 179, 191, 200, 211, 241, 277, 283, 331, 353, 360, 367, 401, 414, 431, 460, 461, 475, 509, 547, 563, 587, 599, 617, 709, 739, 773, 797, 859, 877, 919, 942, 960, 967, 991, 1014 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..58.

EXAMPLE

75 is a term because pi(phi(75)) = pi(40) = 12 and phi(pi(75)) = phi(21) = 12;

0 is a term since pi(phi(0)) = pi(0) = 0 and phi(pi(0)) = phi(0) = 0;

1 is a term since pi(phi(1)) = pi(1) = 0 and phi(pi(1)) = phi(0) = 0.

MAPLE

with(numtheory): a:=proc(n) if pi(phi(n))=phi(pi(n)) then n else fi end: seq(a(n), n=0..1350); # Emeric Deutsch, Apr 30 2006

MATHEMATICA

Select[Range[0, 1030], PrimePi@ EulerPhi@# == EulerPhi@ PrimePi@# &] (* Robert G. Wilson v *)

CROSSREFS

Sequence in context: A184776 A202104 A190246 * A213513 A344168 A239142

Adjacent sequences:  A117480 A117481 A117482 * A117484 A117485 A117486

KEYWORD

nonn

AUTHOR

Luc Stevens (lms022(AT)yahoo.com), Apr 25 2006

EXTENSIONS

More terms from Robert G. Wilson v and Emeric Deutsch, Apr 27 2006

Edited by Jon E. Schoenfield, Feb 06 2019

STATUS

approved

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Last modified June 12 16:55 EDT 2021. Contains 344959 sequences. (Running on oeis4.)