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{\bf Alexander Burstein and Toufik Mansour}
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{\bf Words Restricted by Patterns with at Most 2 Distinct Letters}
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We find generating functions for the number of words avoiding
certain patterns or sets of patterns with at most 2 distinct
letters and determine which of them are equally avoided. We also
find exact numbers of words avoiding certain patterns and provide
bijective proofs for the resulting formulae.
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