A PSCA(v, t, lambda ) is a multiset of permutations of the v-element alphabet {0, dots , v-1}, such that every sequence of t distinct elements of the alphabet appears in the specified order in exactly lambda of the permutations. For v geqslant t geqslant 2, we define g(v, t) to be the smallest positive integer lambda , such that a PSCA(v, t, lambda ) exists. We show that g(6, 3) = g(7, 3) = g(7, 4) = 2 and g(8, 3) = 3. Using suitable permutation representations of groups, we make improvements to the upper bounds on g(v, t) for many values of v leqslant 32 and 3leqslant tleqslant 6. We also prove a number of restrictions on the distribution of symbols among the columns of a PSCA.