1572866domain: NAppears in sequencesa(n) = 6*4^n + 2.at n=9A140788a(n) = 3*2^n + 2.at n=19A1640941/4 the number of (n+1) X 4 0..2 arrays with every 2 X 2 subblock having distinct clockwise edge differences.at n=39A209722a(n) = 3*2^n - 2*(-1)^n.at n=19A259713