A122497 - OEIS

%I #25 Feb 13 2018 02:48:24

%S 1,2,1,1,2,2,1,2,1,1,2,1,2,2,1,1,2,2,1,2,1,1,2,2,1,1,2,1,2,2,1,2,1,1,

%T 2,1,2,2,1,1,2,2,1,2,1,1,2,1,2,2,1,2,1,1,2,2,1,1,2,1,2,2,1,1,2,2,1,2,

%U 1,1,2,2,1,1,2,1,2,2,1,2,1,1,2,1,2,2,1,1,2,2,1,2,1,1,2,2,1,1,2,1,2,2,1,1,2

%N Let f(S) denote the interchange of 1's and 2's in S. Let S_0 = 1, S_{N+1} = f(S_N).S_N, where the dot indicates concatenation. Sequence gives S_0.S_1.S_2.S_3....

%C An alternating triangular Morse-Thue sequence based on A010060 using {1,2} instead of {0,1} substitutions.

%H G. C. Greubel, <a href="/A122497/b122497.txt">Table of n, a(n) for the first 13 rows, flattened</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Thue-MorseConstant.html">Thue-Morse Constant</a>

%F a(n) = A059448(n) + 1. - _Filip Zaludek_, Dec 10 2016

%e The first few S_i are:

%e 1

%e 2, 1

%e 1, 2, 2, 1

%e 2, 1, 1, 2, 1, 2, 2, 1

%e 1, 2, 2, 1, 2, 1, 1, 2, 2, 1, 1, 2, 1, 2, 2, 1

%t ThueMorse[n_, b_] := Nest[Flatten[ # /. {1 -> {1, 2}, 2 -> {2, 1}}] &, {b}, n] a = Table[ThueMorse[n, 1 + Mod[n, 2]], {n, 0, 7}] Flatten[a]

%Y Cf. A010060, A014571, A014572, A074072, A074073.

%K nonn,tabf

%O 1,2

%A _Roger L. Bagula_, Sep 15 2006

%E Edited by _N. J. A. Sloane_, May 22 2007