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A122497
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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....
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0
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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
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| An alternating triangular Morse -Thue sequence based on A010060 using {1,2} instead of {0,1} substitutions.
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LINKS
| Eric Weisstein's World of Mathematics, Thue-Morse Constant
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FORMULA
| 1->)1,2} 2->{2,1} a(n) = ThueMorse[n, 1 + Mod[n, 2]]
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EXAMPLE
| The first few S_i are:
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
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MATHEMATICA
| 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]
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CROSSREFS
| Cf. A010060, A014571, A014572, A074072, A074073.
Sequence in context: A049705 A060236 A006345 * A154402 A177025 A023396
Adjacent sequences: A122494 A122495 A122496 * A122498 A122499 A122500
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KEYWORD
| nonn
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AUTHOR
| Roger Bagula (rlbagulatftn(AT)yahoo.com), Sep 15 2006
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EXTENSIONS
| Edited by N. J. A. Sloane (njas(AT)research.att.com), May 22 2007
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