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%I #9 Feb 06 2019 02:25:19
%S 0,1,3,4,5,8,10,11,17,20,22,30,31,41,50,59,67,75,83,109,127,157,174,
%T 179,191,200,211,241,277,283,331,353,360,367,401,414,431,460,461,475,
%U 509,547,563,587,599,617,709,739,773,797,859,877,919,942,960,967,991,1014
%N Numbers k for which pi(phi(k)) equals phi(pi(k)).
%e 75 is a term because pi(phi(75)) = pi(40) = 12 and phi(pi(75)) = phi(21) = 12;
%e 0 is a term since pi(phi(0)) = pi(0) = 0 and phi(pi(0)) = phi(0) = 0;
%e 1 is a term since pi(phi(1)) = pi(1) = 0 and phi(pi(1)) = phi(0) = 0.
%p 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
%t Select[Range[0, 1030], PrimePi@ EulerPhi@# == EulerPhi@ PrimePi@# &] (* _Robert G. Wilson v_ *)
%K nonn
%O 1,3
%A Luc Stevens (lms022(AT)yahoo.com), Apr 25 2006
%E More terms from _Robert G. Wilson v_ and _Emeric Deutsch_, Apr 27 2006
%E Edited by _Jon E. Schoenfield_, Feb 06 2019
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