\magnification=1440 \font\bigtenrm=cmr10 scaled\magstep4 Abstract for Aviezri S.\ Fraenkel and R.\ Jamie Simpson, How Many Squares Must a Binary Sequence Contain? Let $g(n)$ be the length of a longest binary string containing at most $n$ distinct squares (two identical adjacent substrings). Then $g(0)=3$ (010 is such a string), $g(1)=7$ (0001000) and $g(2)=18$ (010011000111001101). How does the sequence $\bigl\{g(n) \bigr\}$ behave? We give a complete answer. \bye .