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 A057432 Obtained by reading first the numerator then the denominator of fractions in left-hand half of Stern-Brocot tree (A007305/A007306). 1
 1, 1, 1, 2, 1, 3, 2, 3, 1, 4, 2, 5, 3, 5, 3, 4, 1, 5, 2, 7, 3, 8, 3, 7, 4, 7, 5, 8, 5, 7, 4, 5, 1, 6, 2, 9, 3, 11, 3, 10, 4, 11, 5, 13, 5, 12, 4, 9, 5, 9, 7, 12, 8, 13, 7, 11, 7, 10, 8, 11, 7, 9, 5, 6, 1, 7, 2, 11, 3, 14, 3, 13, 4, 15, 5, 18, 5, 17, 4, 13, 5, 14, 7, 19, 8, 21, 7, 18, 7, 17, 8, 19, 7 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 LINKS N. J. A. Sloane, Stern-Brocot or Farey Tree MATHEMATICA Contribution from Peter Luschny, Apr 27 2009: (Start) sbt[n_]:=Module[{P, L, Y}, P={{1, 0}, {1, 1}}; L={{1, 1}, {0, 1}}; Y={{1, 0}, {0, 1}}; w[b_]:=Fold[ #1.If[ #2==0, L, P]&, Y, b]; u[a_]:={a[[2, 1]]+a[[2, 2]], a[[1, 1]]+a[[1, 2]]}; s[l_]:={l, {Last[l], First[l]}}; Map[s, Map[u, Map[w, Part[Partition[Tuples[{0, 1}, n], 2^(n-1)], 1]]]]] Flatten[Append[{1, 1}, Table[Map[First, sbt[i]], {i, 1, 5}]]] (End) CROSSREFS Cf. A007305, A047679, A007306, A002487, A057431. Sequence in context: A307314 A057940 A097285 * A302295 A215467 A284266 Adjacent sequences:  A057429 A057430 A057431 * A057433 A057434 A057435 KEYWORD nonn,easy AUTHOR N. J. A. Sloane, Sep 08 2000 EXTENSIONS More terms from Alford Arnold, Sep 11 2000 More terms from Joshua Zucker, May 11 2006 STATUS approved

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Last modified January 18 05:26 EST 2022. Contains 350418 sequences. (Running on oeis4.)