There are more than $2^{n/17}$$n$-letter ternary square-free words.

Ekhad, Shalosh B., and Zeilberger, Doron. "There are more than -letter ternary square-free words.." Journal of Integer Sequences [electronic only] 1 (1998): Art. 98.1.9, electronic only-Art. 98.1.9, electronic only. <http://eudml.org/doc/223525>.

@article{Ekhad1998,
author = {Ekhad, Shalosh B., Zeilberger, Doron},
journal = {Journal of Integer Sequences [electronic only]},
language = {eng},
pages = {Art. 98.1.9, electronic only-Art. 98.1.9, electronic only},
publisher = {School of Computer Science, University of Waterloo, Waterloo},
title = {There are more than -letter ternary square-free words.},
url = {http://eudml.org/doc/223525},
volume = {1},
year = {1998},
}

TY - JOUR
AU - Ekhad, Shalosh B.
AU - Zeilberger, Doron
TI - There are more than -letter ternary square-free words.
JO - Journal of Integer Sequences [electronic only]
PY - 1998
PB - School of Computer Science, University of Waterloo, Waterloo
VL - 1
SP - Art. 98.1.9, electronic only
EP - Art. 98.1.9, electronic only
LA - eng
UR - http://eudml.org/doc/223525
ER -