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Search: id:A108122
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| A108122 |
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Lengths of steps in a three-symbol substitution sequence with characteristic polynomial: x^3-x^2-2*x-1. |
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+0
1
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| 1, 1, 1, 4, 7, 16, 34, 73, 157, 337, 724, 1555, 3340, 7174, 15409, 33097, 71089, 152692, 327967, 704440, 1513066
(list; graph; listen)
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OFFSET
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0,4
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COMMENT
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This substitution is unique in that it gives a two part tile that only tiles aperiodically.
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FORMULA
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1->{2}, 2->{3}, 3->{1, 2, 2, 3}
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MATHEMATICA
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s[1] = {2}; s[2] = {3}; s[3] = {1, 2, 2, 3}; t[a_] := Flatten[s /@ a]; p[0] = {1}; p[1] = t[p[0]]; p[n_] := t[p[n - 1]] a0 = Table[Length[p[i]], {i, 0, 20}]
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CROSSREFS
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Sequence in context: A133600 A166865 A051049 this_sequence A027609 A145763 A144916
Adjacent sequences: A108119 A108120 A108121 this_sequence A108123 A108124 A108125
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KEYWORD
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nonn,uned
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AUTHOR
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Roger L. Bagula (rlbagulatftn(AT)yahoo.com), Jun 04 2005
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