2097278domain: NAppears in sequencesa(n) = Sum_{k=1..n} binomial(n,k) * sigma(n,k).at n=6A205812Number of (n+1) X (6+1) 0..1 arrays with nondecreasing x(i,j)-x(i,j-1) in the i direction and nonincreasing x(i,j)-x(i-1,j) in the j direction.at n=19A250740