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%I #11 Oct 30 2019 17:37:28
%S 1,0,2,1,4,0,6,2,5,1,11,0,13,2,5,4,17,1,19,3,9,5,23,2,19,7,15,6,29,0,
%T 31,9,16,10,21,3,37,12,20,8,41,2,43,12,18,15,47,5,41,10,26,14,53,5,36,
%U 13,30,19,59,2,61,20,28,21,44,6,67,21,37,10,71,9,73,25,29,23,56,7,79,16,45
%N a(n) = number of composites coprime to n and <= the n-th composite.
%t c = Select[Range[120], # != 1 && ! PrimeQ[ # ] &];Table[Length[Select[Take[c, n], GCD[ #, n] == 1 &]], {n, Length[c]}] (* _Ray Chandler_, Feb 17 2007 *)
%Y Cf. A002808.
%K nonn
%O 1,3
%A _Leroy Quet_, Feb 11 2007
%E Extended by _Ray Chandler_, Feb 17 2007