23193600

Appears in sequences

• Triangle read by rows: T(n,k) is the number of permutations p of {1,2,...,n} for which the number of j < ceiling(n/2) such that p(j) + p(n+1-j) = n+1 is equal to k (n>=1; 0<=k <=ceiling(n/2)).at n=40A155517
• Number of permutations p of {1,2,...,n} such that p(j) + p(n+1-j) != n+1 for all j.at n=11A155518
• Sequence a(n) gives the number of ways to seat 2n people around a circular table so that person i does not sit across from person n+i for any 1 <= i <= n.at n=5A167406