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Search: id:A091838
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A091838 a(n) = number of images of the border correlation function for binary words of length n (cf. link). +0
1
1, 2, 4, 7, 11, 18, 29, 47, 76, 121, 199, 310, 521, 841, 1364, 2207, 3571, 5776, 9349, 15125, 24476, 39601, 64079, 103682, 167761, 271441, 439204, 710645, 1149851, 1860496 (list; graph; listen)
OFFSET

1,2

COMMENT

Values for even indices seem mysterious, but does A091838(2n+1) = A002878(n), the bisection of Lucas sequence?

LINKS

T. Harju and D. Nowotka, Border correlation of binary words.

FORMULA

a(n) < 2^(n-1)

a(n) <= F(n) + F(n-2) - m where F(i) is the i-th Fibonacci number and m=2 if n is in the set {2i | i >= 0} - {2^j, 3x2^j | j >= 0} - Dirk Nowotka (nowotka(AT)utu.fi), May 16 2004

a(n) seems to be asymptotic to phi^n where phi=(1+sqrt(5))/2.

CROSSREFS

Sequence in context: A003403 A034412 A054352 this_sequence A004696 A018063 A000570

Adjacent sequences: A091835 A091836 A091837 this_sequence A091839 A091840 A091841

KEYWORD

nonn

AUTHOR

Benoit Cloitre (benoit7848c(AT)orange.fr), based on the Harju and Nowotka paper, Mar 10 2004

EXTENSIONS

More terms from Dirk Nowotka (nowotka(AT)utu.fi), May 16 2004

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Last modified November 25 14:49 EST 2009. Contains 167514 sequences.


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