2098480

Appears in sequences

• Number of (n+1) X (3+1) 0..1 arrays with nondecreasing x(i,j)-x(i,j-1) in the i direction and nondecreasing x(i,j)-x(i-1,j) in the j direction.at n=15A250606
• a(n) = Sum_{k=0..floor(n/2)} binomial(k+3,3) * binomial(k,n-2*k)^2.at n=21A377149