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%I #14 May 14 2017 03:15:43
%S 1,2,11,13,17,19,23,25,27,29,31,33,35,37,39,41,43,47,49,51,53,55,57,
%T 59,61,63,65,67,69,71,73,75,77,79,81,83,85,87,89,91,93,94,95,97,99,
%U 101,103,106,107,109,111,113,115,117,118,119,121,122,123,124,125,127,128
%N Numbers for which reduced residue system contains fewer primes than nonprimes.
%C Integers n such that 2*A000720(n) - 2*A001221(n) < A000010(n).
%H G. C. Greubel, <a href="/A048867/b048867.txt">Table of n, a(n) for n = 1..1000</a>
%e Large primes belong to this set. Composites like: n=35 has 2 prime divisors, Phi(35)=24 Pi(35)=11; In reduced residue system 9 primes and 15 nonprimes occur.
%t Select[Range[500], 2*PrimePi[#] - 2*PrimeNu[#] < EulerPhi[#] &] (* _G. C. Greubel_, May 12 2017 *)
%o (PARI) isok(n) = 2*(primepi(n) - omega(n)) < eulerphi(n); \\ _Michel Marcus_, May 13 2017
%Y Cf. A000010, A000720, A001221.
%K nonn
%O 1,2
%A _Labos Elemer_
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