Pattern frequency sequences and internal zeros
Abstract
Consider the number of permutations in the symmetric group on n letters that contain c copies of a given pattern. As c varies (with n held fixed) these numbers form a sequence whose properties we study for the monotone patterns and the patterns 1, l, l1, ..., 2. We show that, except for the patterns 1, 2 and 2, 1 where the sequence is wellknown to be log concave, there are infinitely many n where the sequence has internal zeros.
 Publication:

arXiv Mathematics eprints
 Pub Date:
 April 2001
 arXiv:
 arXiv:math/0104098
 Bibcode:
 2001math......4098B
 Keywords:

 Mathematics  Combinatorics;
 05A05 (Primary) 05A20;
 05E99;
 06A07 (Secondary)
 EPrint:
 24 pages