720576domain: NAppears in sequencesa(n) = 6*a(n-1) - 6*a(n-2) for n > 1; a(0) = 4, a(1) = 15.at n=8A164310Number of (n+1) X 4 0..2 arrays with every 2 X 3 or 3 X 2 subblock having exactly two equal edges, and new values 0..2 introduced in row major order.at n=9A206210