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A093382 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). 6
11, 31, 199 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Doesn't the binary sequence 000010011001110011101010101010101010101100110 demonstrate that a(2) >= 45? - R. J. Mathar, 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, May 13 2008
a(4) >= 376843. - Bert Dobbelaere, May 25 2024
REFERENCES
a(1) - a(3) computed by R. Dougherty, who finds that a(4) >= 187205.
LINKS
H. M. Friedman, Long finite sequences, J. Comb. Theory, A 95 (2001), 102-144.
EXAMPLE
a(1) = 11 from 01110000000.
CROSSREFS
See A093383-A093386 for illustrations of a(2) and a(3). Cf. A014221, A094091.
Sequence in context: A144727 A002535 A128337 * A098264 A023279 A068715
KEYWORD
nonn,bref,nice,more
AUTHOR
N. J. A. Sloane, Apr 29 2004
STATUS
approved

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Last modified June 24 12:27 EDT 2024. Contains 373677 sequences. (Running on oeis4.)