A178047 Consider the Farey tree A049455/A049456; a(n) = row at which the denominator n first appears (assumes first row is labeled row 0).

0, 1, 2, 3, 3, 5, 4, 4, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 7, 6, 7, 7, 7, 7, 7, 7, 8, 7, 7, 7, 8, 8, 7, 8, 8, 8, 9, 8, 8, 8, 9, 8, 8, 8, 8, 8, 9, 8, 8, 9, 9, 9, 10, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 10, 9, 9, 9, 9, 10, 10, 9, 9, 9, 10, 10, 10, 10, 10, 10, 10, 9, 11, 10, 10, 10, 10, 10, 11

Offset: 1

Author

N. J. A. Sloane, Dec 16 2010

Keywords

• nonn

Comments

Equals A178031 - 1. See that entry for further information.

Links

• Richard J. Mathar, The Kepler binary tree of reduced fractions, 2017.

Crossrefs

Cf. A295783 (frequencies of this).