page of posts code

How do I alter this when I got up to 20 different pages of posts?

// if this is a certain page ID, then set the category to a specific category id.
if (is_page('2272') )
{
  $cat = array(8);
}
elseif (is_page('2042') )
{
  $cat = array(14);
}
else
{
  $cat = '';
}