536870942domain: NAppears in sequencesa(n) = 2^n + n + 1.at n=29A005126Number of (n+1) X (4+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=27A250738