244878791domain: NPropertiesPrimalityPrimeyesAppears in sequencesNumber of (1+1)X(n+1) 0..1 arrays with nondecreasing x(i,j)+x(i,j-1) in the i direction and nondecreasing min(x(i,j),x(i-1,j)) in the j direction.at n=21A250730Prime numbersat n=13414311