143760domain: NAppears in sequencesNumber of n X 4 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 0 1 and 1 0 1 vertically.at n=23A207449Number of (w,x,y,z) with all terms in {1,...,n} and w*x+y*z<n^2.at n=20A212111