1,3

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

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.

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

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

Sequence in context: A184776 A202104 A190246 * A213513 A344168 A239142

Adjacent sequences: A117480 A117481 A117482 * A117484 A117485 A117486

nonn

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

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

Edited by Jon E. Schoenfield, Feb 06 2019

approved