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%I #9 Oct 10 2019 15:31:58
%S 1,1,1,2,2,3,3,3,4,3,5,3,6,5,5,6,8,3,9,7,6,8,11,4,11,9,7,10,14,3,15,
%T 11,9,11,14,6,18,13,10,11,20,6,21,14,9,15,23,8,23,13,15,17,26,10,22,
%U 16,17,18,29,7,30,20,15,21,27,8,33,23,20,17,35,12,36,23,17,24,30,12,39,21,24
%N a(1)=1. a(n) = the number of terms from among the first floor(n/2) terms of the sequence which are coprime to n.
%e The first floor(15/2) terms of the sequence are 1,1,1,2,2,3,3. Of these, five terms (1,1,1,2,2) are coprime to 15. So a(15) = 5.
%t f[l_List] := Block[{n = Length[l] + 1},Append[l, Length[Select[Take[l, Floor[n/2]], GCD[ #, n] == 1 &]]]];Nest[f, {1}, 80] (* _Ray Chandler_, Dec 11 2006 *)
%Y Cf. A125843.
%K nonn
%O 1,4
%A _Leroy Quet_, Dec 10 2006
%E Extended by _Ray Chandler_, Dec 11 2006
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