Avoiding Three Consecutive Blocks of the Same Size and Same Sum
Julien Cassaigne, James D. Currie, Luke Schaeffer, Jeffrey O. Shallit · Journal of the ACM · 2014
We show that there exists an infinite word over the alphabet {0, 1, 3, 4} containing no three consecutive blocks of the same size and the same sum. This answers an open problem of Pirillo and Varricchio from 1994.