8463633domain: NAppears in sequencesa(n) = -4*a(n-3) + 11*a(n-2) - a(n-1), a(0) = 13, a(1) = -19, a(2) = 162.at n=10A153266Number of (n+1) X (1+1) 0..1 arrays with each 2 X 2 subblock having clockwise pattern 0000 0011 or 0101.at n=21A259215