2631600

Appears in sequences

• Number of permutations of the multiset {1,1,2,2,...,n,n} with no two consecutive terms equal.at n=6A114938
• Square array A(n,k), n >= 1, k >= 1, read by antidiagonals, where A(n,k) is the number of permutations of n copies of 1..k with no element equal to another within a distance of 1.at n=22A322093