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A057432 Obtained by reading first numerator then 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

Table of n, a(n) for n=0..92.

N. J. A. Sloane, Stern-Brocot or Farey Tree

Index entries for sequences related to Stern's sequences

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: A108663 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 19 20:24 EST 2019. Contains 319310 sequences. (Running on oeis4.)