273459449270domain: NAppears in sequencesNumber of (n+1)X(3+1) 0..1 arrays x(i,j) with row sums sum{x(i,j), j=1..3+1} nondecreasing, and column sums sum{i*x(i,j), i=1..n+1} nondecreasing.at n=13A233060