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2, 4, 6, 9, 11, 14, 16, 18, 21, 23, 26, 28, 30, 33, 35, 38, 40, 43, 45, 47, 50, 52, 55, 57, 59, 62, 64, 67, 69, 72, 74, 76, 79, 81, 84, 86, 88, 91, 93, 96, 98, 100, 103, 105, 108, 110, 113, 115, 117, 120, 122, 125, 127, 129, 132, 134, 137, 139, 142, 144, 146
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OFFSET
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1,1
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COMMENTS
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Conjecture: -1 + sqrt(2) < n*r - a(n) < sqrt(2) for n>=1, where r = 1 + sqrt(2).
Proof of the conjecture: the sequence d:=A285073 can be written as d=01c, where c is the homogeneous Sturmian sequence with slope sqrt(2)-1 (see comments of A285073).
In general, a homogeneous Sturmian sequence (floor((n+1)r)-floor(nr)) gives the positions of 1 in the Beatty sequence b=(floor((n+1)s)), where s=1/r.
In our case s=1+sqrt(2). It follows that for n=0,1,… one has a(n+2) = floor((n+1)(1+sqrt(2)) + 2, which directly implies the conjecture. (End)
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LINKS
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EXAMPLE
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As a word, A285073 = 01010...,..., in which 1 is in positions 2,4,6,9,11,...
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MATHEMATICA
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s = Nest[Flatten[# /. {0 -> {1, 0}, 1 -> {0, 1, 0}}] &, {0}, 14]; (* A285073 *)
Flatten[Position[s, 0]]; (* A285074 *)
Flatten[Position[s, 1]]; (* A285075 *)
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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