Search: id:A127940
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%I A127940
%S A127940 1,1,1,2,3,8,22,71,93,638,9144,26821,2373690,11013191,950468551,
%T A127940 23819080360,4860600739719,18887557655957,23748158395676,
%U A127940 102452785866447,1153981434332852712,722919835385951370578
%N A127940 a(n) = denominator of b(n), where b(1)=1, b(n+1) = sum{k|n} 1/b(k).
%H A127940 Leroy Quet, <a href="http://www.prism-of-spirals.net/">Home Page</a> 
               (listed in lieu of email address)
%e A127940 {b(n)}:1,1,2,3/2,8/3,11/8,71/22,93/71,...So b(7) = sum{k|6} 1/b(k) = 
               1/b(1) + 1/ b(2) + 1/b(3) + 1/b(6) = 1 + 1 + 1/2 + 8/11 = 71/22.
%t A127940 f[l_List] := Block[{n = Length[l], d = Divisors[n]},Append[l, Sum[1/l[[d[[i]]]], 
               {i, Length[d]}]]];Denominator[Nest[f, {1}, 22]] (*Chandler*)
%Y A127940 Cf. A127939.
%Y A127940 Sequence in context: A006545 A121050 A089402 this_sequence A006796 A006076 
               A086628
%Y A127940 Adjacent sequences: A127937 A127938 A127939 this_sequence A127941 A127942 
               A127943
%K A127940 frac,nonn
%O A127940 1,4
%A A127940 Leroy Quet Feb 08 2007
%E A127940 Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Feb 09 2007

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