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A178042 Consider the weighted Farey tree A177405/A177407; a(n) = row at which the denominator 2n+1 first appears (assumes first row is labeled row 1).

%I A178042 #6 Mar 30 2012 16:51:57
%S A178042 1,2,3,3,3,4,4,5,4,4,5,5,5,4,5,5,6,6,6,6,5,5,6,5,6,7,5,5,7,6,7,6,6,6,
%T A178042 6,6,6,6,6,6,5,6,7,8,7,7,7,7,7,6,7,6,7,7,7,7,6,7,8,7,7,7,7,7,7,7,6,7,
%U A178042 6,8,8,7,7,8,8,7,8,7,7,7,6,6,8,7,7,7,8,8,8,7,7,7,8,8,7,8,8,8,7,8,8
%N A178042 Consider the weighted Farey tree A177405/A177407; a(n) = row at which the denominator 2n+1 first appears (assumes first row is labeled row 1).
%C A178042 Equals A177903 + 1. See that entry for further information.
%K A178042 nonn
%O A178042 0,2
%A A178042 _N. J. A. Sloane_, Dec 16 2010