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Search: id:A093382
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| A093382 |
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a(n) = length k of longest binary sequence x(1) ... x(k) such that for no n <= i < j <= k/2 is x(i) ... x(2i) a subsequence of x(j) ... x(2j). |
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+0
7
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OFFSET
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1,1
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COMMENT
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Doesn't the binary sequence 000010011001110011101010101010101010101100110 demonstrate that a(2)>=45 ? - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jul 29 2007 Answer: No - see the following comment.
The sequence of length 45 above does not satisfy the requirements of the definition: Subsequences are not required to be consecutive. Therefore it cannot show a(2)>=45. In the sequence we find for i=2, j=3: x(i..2i) is 000; x(j..2j) is 001001; and 000 is a subsequence of 001001. - Don Reble (djr(AT)nk.ca), May 13 2008
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REFERENCES
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a(1) - a(3) computed by R. Dougherty, who finds that a(4) >= 187205.
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LINKS
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H. M. Friedman, Long finite sequences, J. Comb. Theory, A 95 (2001), 102-144.
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EXAMPLE
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a(1) = 11 from 01110000000.
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CROSSREFS
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See A093383-A093386 for illustrations of a(2) and a(3). Cf. A014221, A094091.
Sequence in context: A144727 A002535 A128337 this_sequence A098264 A023279 A068715
Adjacent sequences: A093379 A093380 A093381 this_sequence A093383 A093384 A093385
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KEYWORD
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nonn,bref,nice,more
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Apr 29 2004
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