213010026700domain: NAppears in sequencesNumber of (1+1)X(n+1) 0..3 arrays x(i,j) with row sums sum{x(i,j), j=1..n+1} nondecreasing, and column sums sum{i*x(i,j), i=1..1+1} nondecreasing.at n=18A232887