15459444domain: NAppears in sequencesTriangle T(n,m)=m*n*binomial(m+n,m)^2/(2*(m+n)) read by rows.at n=33A131635Number of commutative binary operators defined on the finite chain L_n={0,1,...n}, C:L_n^2-> L_n, which are increasing in each argument, and satisfy the boundary conditions C(0,n)=C(n,0)=0 and C(n,n)=n.at n=5A366540