873964

Appears in sequences

• a(n) = Sum_{k=0..floor(n/2)} T(n-k, k), T given by A026692.at n=26A026702
• a(0) = 1; a(n) = Sum_{k=1..n} (-1)^(k+1) * binomial(n,k)^2 * binomial(2*k,k) * a(n-k).at n=6A336271
• Square array read by descending antidiagonals. T(n,k) is the number of ways to separate the columns of an ordered pair of n-permutations (that have been written as a 2 X n array, one atop the other) into k cells so that no cell has a column rise. For n >= 0, k >= 0.at n=42A340986