976144domain: NAppears in sequencesn, ps(n), ps^2(n), ..., ps^9(n) forms an increasing ps-sequence of length 10.at n=21A158918Number of n X 2 0..1 arrays avoiding 0 0 1 and 0 1 0 horizontally and 0 0 1 and 1 0 0 vertically.at n=13A207436