The Enumeration of Permutations With a Prescribed Number of   ``Forbidden'' Patterns
  We initiate a general approach for the fast enumeration of permutations with a prescribed number of occurrences of `forbidden' patterns, that seems to indicate that the enumerating sequence is always P-recursive. We illustrate the method completely in terms of the patterns `abc',`cab' and `abcd'. 
John Noonan (Mt. Vernon Nazarene College) and Doron Zeilberger (Temple   University)