Search: id:A125842
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%I A125842
%S A125842 1,1,1,2,2,3,3,3,4,3,5,3,6,5,5,6,8,3,9,7,6,8,11,4,11,9,7,10,14,3,15,11,
%T A125842 9,11,14,6,18,13,10,11,20,6,21,14,9,15,23,8,23,13,15,17,26,10,22,16,17,
%U A125842 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 A125842 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.
%H A125842 Leroy Quet, <a href="http://www.prism-of-spirals.net/">Home Page</a> 
               (listed in lieu of email address)
%e A125842 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 A125842 f[l_List] := Block[{n = Length[l] + 1},Append[l, Length[Select[Take[l, 
               Floor[n/2]], GCD[ #, n] == 1 &]]]];Nest[f, {1}, 80] (*Chandler*)
%Y A125842 Cf. A125843.
%Y A125842 Sequence in context: A000121 A049846 A086712 this_sequence A029865 A072644 
               A070082
%Y A125842 Adjacent sequences: A125839 A125840 A125841 this_sequence A125843 A125844 
               A125845
%K A125842 nonn
%O A125842 1,4
%A A125842 Leroy Quet Dec 10 2006
%E A125842 Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Dec 11 2006

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