33554336domain: NAppears in sequencesNumber of (n+1)X(1+1) 0..1 arrays with every 2X2 subblock ne-sw antidiagonal difference nondecreasing horizontally and nw+se diagonal sum nondecreasing vertically.at n=20A258547a(n) = 4 + 2^n - 4*n.at n=24A302689