527283domain: NAppears in sequencesNumber of (n+1) X (3+1) 0..1 arrays with every 2 X 2 subblock ne-sw antidiagonal difference nondecreasing horizontally and nw+se diagonal sum nondecreasing vertically.at n=26A258549The number of spanning trees of the ladder graph L_n up to automorphisms of L_n.at n=11A363165