1879862domain: NAppears in sequencesNumber of happy numbers without zeros and with digits in nondecreasing order <= 10^n.at n=21A219667Number of (5+1) X (n+1) 0..1 arrays with nondecreasing min(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=9A250802