

A057432


Obtained by reading first numerator then denominator of fractions in lefthand half of SternBrocot 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
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OFFSET

0,4


LINKS

Table of n, a(n) for n=0..92.
N. J. A. Sloane, SternBrocot 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^(n1)], 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



