Determine the number of permutations (p1
) of 1,2, ...7; such that for all k 1≤k≤6, (p1
is not a permutation of (1,2, ...k); i.e., p1
) is not a permutation of (1,2), etc.
What would be the answer if we specify 1≤k<6 instead?
(In reply to solution?
Nope; the permutation (1,2,3,4,5,7,6) doesn't have 7 at the last position, but doesn't fulfill the other conditions.