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

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, 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, 10, 10, 10, 10, 10, 10, 10, 10, 10

Offset

1,2

Comments

Computed by Alan Wechsler, Dec 16, 2010.

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

References

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

Links

Bo Gyu Jeong, Table of n, a(n) for n = 1..10000

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

Crossrefs

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

Sequence in context: A180046 A008329 A064558 * A008328 A298933 A365851

Adjacent sequences: A178028 A178029 A178030 * A178032 A178033 A178034

Keyword

nonn

Author

N. J. A. Sloane, Dec 16 2010

Extensions

More terms from Bo Gyu Jeong, Oct 20 2012

Status

approved