870280

Appears in sequences

• Number of (3+1) X (n+1) 0..1 arrays with nondecreasing x(i,j)+x(i,j-1) in the i direction and nondecreasing absolute value of x(i,j)-x(i-1,j) in the j direction.at n=13A250785
• a(n) = (1/3)*A290906(n).at n=12A290907