Search: id:A127941
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%I A127941
%S A127941 1,1,2,3,19,25,12091,942579,802405765442,9728923151534907,
%T A127941 40387361143971542769608346059516047956596,
%U A127941 16013133965687337121814734147004294320263129575
%N A127941 a(n) = numerator of b(n), where b(1)=1, b(n) = sum{1<=k<n,GCD(k,n)=1} 
               1/b(k).
%H A127941 Leroy Quet, <a href="http://www.prism-of-spirals.net/">Home Page</a> 
               (listed in lieu of email address)
%e A127941 {b(n)}: 1,1,2,3/2,19/6,25/19,12091/2850,... Since 1 and 5 are the positive 
               integers which are coprime to 6 and are < 6, then b(6) = 1/b(1) + 
               1/b(5) = 1 + 6/19 = 25/19.
%t A127941 f[l_List] := Block[{n = Length[l] + 1, d},d = Select[Range[n - 1], GCD[ 
               #, n] == 1 &];Append[l, Sum[1/l[[d[[i]]]], {i, Length[d]}]]];Numerator[Nest[f, 
               {1}, 12]] (*Chandler*)
%Y A127941 Cf. A127942.
%Y A127941 Sequence in context: A038957 A141750 A090476 this_sequence A140555 A058912 
               A040145
%Y A127941 Adjacent sequences: A127938 A127939 A127940 this_sequence A127942 A127943 
               A127944
%K A127941 frac,nonn
%O A127941 1,3
%A A127941 Leroy Quet Feb 08 2007
%E A127941 Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Feb 09 2007

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