For each integer n 2 letan be the number of permutations
Chapter 9, Problem 9.111(choose chapter or problem)
For each integer n 2 letan be the number of permutations of {1,2,3,...,n} in which no number is more than one place removed from its natural position. Thus a1 =1 since the one permutation of {1}, namely 1, does not move 1 from its natural position. Alsoa2 =2 since neither of the two permutations of {1,2}, namely 12 and 21, moves either number more than one place from its natural position. a. Find a3. b. Find a recurrence relation for a1,a2,a3,....
Unfortunately, we don't have that question answered yet. But you can get it answered in just 5 hours by Logging in or Becoming a subscriber.
Becoming a subscriber
Or look for another answer