Permutations restricted by two distinct patterns of length three

Abstract

Define Sn(R; T) to be the set of permutations on n letters which avoid all patterns in the set R and contain each pattern in the multiset T exactly once. In this paper we enumerate Sn(α;β) and Sn(∅; {α, β}) for all α ≠ β ∈ S3. © 2001 Academic Press.