

A082380


Number of 7/3+powerfree words over the alphabet {0,1}.


3



1, 2, 4, 6, 10, 14, 20, 30, 38, 50, 64, 86, 108, 136, 178, 222, 276, 330, 408, 500, 618, 774, 962, 1178, 1432, 1754, 2160, 2660, 3292
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OFFSET

0,2


LINKS

Table of n, a(n) for n=0..28.
J. KarhumÃ¤ki and J. Shallit, Polynomial vs Exponential Growth in RepetitionFree Binary Words
A. M. Shur, Growth properties of powerfree languages, Computer Science Review, Vol. 6 (2012), 187208.
A. M. Shur, Numerical values of the growth rates of powerfree languages, arXiv:1009.4415 [cs.FL], 2010.


FORMULA

Let L = lim a(n)^(1/n); then L exists since a(n) is submultiplicative. 1.2206318 < L < 1.22064482 (Shur 2012); the gap between the bounds can be made less than any given constant. Empirically, the upper bound is precise: L=1.2206448... .  Arseny Shur, Apr 26 2015


CROSSREFS

Cf. A038952, A028445, A007777, A082379.
Sequence in context: A103257 A103259 A280131 * A238871 A323595 A136460
Adjacent sequences: A082377 A082378 A082379 * A082381 A082382 A082383


KEYWORD

nonn


AUTHOR

Ralf Stephan, Apr 10 2003


EXTENSIONS

Changed name by Jeffrey Shallit, Sep 26 2014


STATUS

approved



