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A291365 Number of closed Sturmian words of length n. 0
2, 2, 4, 6, 12, 16, 26, 36, 52, 64, 86, 108, 142, 170, 206, 242 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

A word is closed if it has length 1 or contains a proper factor that occurs only as a prefix and as a suffix in it.

LINKS

Table of n, a(n) for n=1..16.

Michelangelo Bucci, Alessandro De Luca, Gabriele Fici, Enumeration and structure of trapezoidal words, Theor. Comput. Sci. 468: 12-22 (2013).

EXAMPLE

For n=4, the closed Sturmian words of length n are "aaaa", "abab", "abba", "baab", "baba" and "bbbb".

CROSSREFS

Cf. A260881.

Sequence in context: A228892 A267610 A336940 * A154779 A332983 A010101

Adjacent sequences:  A291362 A291363 A291364 * A291366 A291367 A291368

KEYWORD

nonn,more

AUTHOR

Gabriele Fici, Aug 23 2017

STATUS

approved

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Last modified September 18 13:51 EDT 2021. Contains 347527 sequences. (Running on oeis4.)