Determine the number of permutations (p₁, p₂,...p₇) of 1,2, ...7; such that for all k 1≤k≤6, (p₁, p₂,... p_k) is not a permutation of (1,2, ...k); i.e., p₁≠1; (p₁, p₂) is not a permutation of (1,2), etc.

What would be the answer if we specify 1≤k<6 instead?

Please disregard this comment.
The problem is now displayed as submitted in the original form.

 

 

 

Edited on September 20, 2006, 2:19 pm

Posted by K Sengupta on 2006-09-20 14:15:33