A122497 - OEIS

A122497

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....

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, 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, 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

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OFFSET

1,2

COMMENTS

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

LINKS

G. C. Greubel, Table of n, a(n) for the first 13 rows, flattened

Eric Weisstein's World of Mathematics, Thue-Morse Constant

FORMULA

a(n) = A059448(n) + 1. - Filip Zaludek, Dec 10 2016

EXAMPLE

The first few S_i are: