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%I #28 Dec 27 2019 07:46:19
%S 0,0,0,0,1,0,2,0,2,1,5,0,6,1,3,2,9,0,10,1,5,3,13,0,11,4,9,4,18,0,19,5,
%T 10,6,14,2,24,7,13,5,27,1,28,7,11,9,31,2,27,6,18,10,36,3,25,9,21,13,
%U 41,1,42,13,19,14,31,4,47,14,26,7,50,5,51,16,20,16,40,5,56,11,32,19,59,3
%N Number of composite numbers <= n and relatively prime to n.
%C 30 is the largest number n with the property that if 1 < k < n and k is relatively prime to n, then k is prime. In other words, a(30) = 0 and if m > 30, then a(m) > 0. - _Jonathan Sondow_, Dec 08 2012
%H Michael De Vlieger, <a href="/A036997/b036997.txt">Table of n, a(n) for n = 1..10000</a>
%F A048864(n) = a(n) + 1. - _Peter Luschny_, Oct 22 2010
%t Table[ Count[ Select[ Range[ n ], GCD[ #, n ]===1& ], q_/;!(PrimeQ[ q ]||q===1) ], {n, 180} ]
%Y Cf. A048597 (indices where a(n) = 0), A048865 (number of primes p < n that are relatively prime to n).
%K nonn
%O 1,7
%A _Wouter Meeussen_
%E Minor edits by _Ray Chandler_, Mar 16 2010
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