Academic Editor: Ram N. Mohapatra
Copyright © 2010 Hasan Furkan and Celal Çakan. This is an open access article distributed under the
Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
The -core of a double sequence has been defined and it is studied by many authors. In
this paper, we have determined two permutations and on the set of natural numbers for which for all .