21599745

Appears in sequences

• Number of permutations s of {1,2,...,n} such that |s(i)-i|>1 for each i=1,2,...,n.at n=12A001883
• Number T(n,k) of permutations p of [n] such that |p(j)-j| >= k (for all j in [n]); triangle T(n,k), n >= 0, 0 <= k <= floor(n/2), read by rows.at n=44A306543