786839961600domain: NAppears in sequencesa(n) = ((2 + sqrt(2))^n - (2 - sqrt(2))^n)^2/8.at n=12A144844Number of 4Xn 0..1 arrays avoiding 0 0 0 and 0 1 0 horizontally and 0 0 1 and 1 0 1 vertically.at n=19A207601