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A057431 Obtained by reading first numerator then denominator of fractions in full Stern-Brocot tree (A007305/A047679). 2
0, 1, 1, 0, 1, 1, 1, 2, 2, 1, 1, 3, 2, 3, 3, 2, 3, 1, 1, 4, 2, 5, 3, 5, 3, 4, 4, 3, 5, 3, 5, 2, 4, 1, 1, 5, 2, 7, 3, 8, 3, 7, 4, 7, 5, 8, 5, 7, 4, 5, 5, 4, 7, 5, 8, 5, 7, 4, 7, 3, 8, 3, 7, 2, 5, 1, 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, 6, 5 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,8

COMMENTS

When presented in this way, every row (e.g. row 3, 1 3 2 3 3 2 3 1) is a palindrome. - Joshua Zucker, May 11 2006

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..10000

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

Index entries for sequences related to Stern's sequences

MAPLE

F:= proc(n) option remember; local t;

      t:= l-> [[l[1], [l[1][1]+l[2][1], l[1][2]+l[2][2]], l[2]],

               [l[2], [l[2][1]+l[3][1], l[2][2]+l[3][2]], l[3]]][];

      if n=0 then [[[ ], [0, 1], [ ]], [[ ], [1, 0], [ ]]]

    elif n=1 then [[[0, 1], [1, 1], [1, 0]]]

             else map(t, F(n-1))

      fi

    end:

aa:= n-> map(x-> x[], [seq(map(x-> x[2], F(j))[], j=0..n)])[]:

aa(7);   # aa(n) gives the first 2^(n+1)+2 terms

# Alois P. Heinz, Jan 13 2011

CROSSREFS

Cf. A007305, A047679, A007306, A002487, A057432.

Sequence in context: A047110 A288533 A093869 * A179541 A057060 A198380

Adjacent sequences:  A057428 A057429 A057430 * A057432 A057433 A057434

KEYWORD

nonn,look,easy

AUTHOR

N. J. A. Sloane, Sep 08 2000

EXTENSIONS

More terms from Joshua Zucker, May 11 2006

STATUS

approved

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Last modified January 20 14:40 EST 2019. Contains 319333 sequences. (Running on oeis4.)