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A317988 Farey fraction tree, reading each fraction's numerator first, then its denominator. 0
0, 1, 1, 1, 1, 2, 1, 3, 2, 3, 1, 4, 3, 4, 1, 5, 2, 5, 3, 5, 4, 5, 1, 6, 5, 6, 1, 7, 2, 7, 3, 7, 4, 7, 5, 7, 6, 7, 1, 8, 3, 8, 5, 8, 7, 8, 1, 9, 2, 9, 4, 9, 5, 9, 7, 9, 8, 9, 1, 10, 3, 10, 7, 10, 9, 10, 1, 11, 2, 11, 3, 11, 4, 11, 5, 11, 6, 11, 7, 11, 8, 11, 9, 11, 10, 11, 1, 12, 5, 12, 7, 12, 11, 12 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

COMMENTS

0 < a(2n-1)/a(2n) < 1 for n > 2.

This appears to be A038568 preceded by 0,1,1. - Peter Kagey, Jan 09 2022

LINKS

Table of n, a(n) for n=1..94.

FORMULA

0,1 followed by the interleaving of A038566 & A038567.

EXAMPLE

Farey fraction tree begins:

  0/1                                             1/1

                          1/2

                  1/3             2/3

              1/4                     3/4

           1/5       2/5       3/5       4/5

          1/6                             5/6

         1/7    2/7    3/7   4/7    5/7    6/7

        1/8         3/8         5/8         7/8

       1/9   2/9       4/9   5/9       7/9   8/9

      1/10      3/10                7/10     9/10

  ...

MATHEMATICA

Table[ If[ GCD[n, d] == 1, {n, d}, {}], {d, 0, 12}, {n, 0, d}] // Flatten

CROSSREFS

Cf. A038566, A038567, A038568.

Sequence in context: A302295 A215467 A284266 * A038568 A071912 A070940

Adjacent sequences:  A317985 A317986 A317987 * A317989 A317990 A317991

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Oct 03 2018

STATUS

approved

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Last modified October 2 08:34 EDT 2022. Contains 357191 sequences. (Running on oeis4.)