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 A178031 Consider the Farey tree A006842/A006843; a(n) = row at which the denominator n first appears (assumes first row is labeled row 1). 3

%I

%S 1,2,3,4,4,6,5,5,6,6,6,6,6,7,7,7,7,7,7,8,7,8,8,8,8,8,8,9,8,8,8,9,9,8,

%T 9,9,9,10,9,9,9,10,9,9,9,9,9,10,9,9,10,10,10,11,9,10,10,10,10,10,10,

%U 10,10,10,10,10,10,10,10,10

%N Consider the Farey tree A006842/A006843; a(n) = row at which the denominator n first appears (assumes first row is labeled row 1).

%C Computed by Alan Wechsler, Dec 16, 2010.

%C Richard C. Schroeppel also asked about the analogous sequence giving the last occurrence of denominator n.

%D Based on a posting by Richard C. Schroeppel to the Math Fun Mailing List, Dec 15 2010.

%H Bo Gyu Jeong, <a href="/A178031/b178031.txt">Table of n, a(n) for n = 1..10000</a>

%H Richard J. Mathar, <a href="http://www.mpia.de/~mathar/public/mathar20171127.pdf">The Kepler binary tree of reduced fractions</a>, 2017.

%Y See A178047 for another version. Cf. A006842, A006843, A177903, A178042.

%K nonn

%O 1,2

%A _N. J. A. Sloane_, Dec 16 2010

%E More terms from _Bo Gyu Jeong_, Oct 20 2012

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Last modified November 23 21:51 EST 2020. Contains 338603 sequences. (Running on oeis4.)