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 A178047 Consider the Farey tree A006842/A006843; a(n) = row at which the denominator n first appears (assumes first row is labeled row 0). 2
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 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 (conjectured frequencies of this). Sequence in context: A056149 A167494 A091238 * A122954 A268087 A257004 Adjacent sequences:  A178044 A178045 A178046 * A178048 A178049 A178050 KEYWORD nonn AUTHOR N. J. A. Sloane, Dec 16 2010 STATUS approved

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Last modified November 23 16:18 EST 2020. Contains 338590 sequences. (Running on oeis4.)