2764619domain: NAppears in sequencesa(n) = Sum_{k=0..floor(n/4)} C(n-k,3*k) * 2^k * 3^(n-4*k).at n=12A099787Number of n X n binary arrays symmetric under horizontal reflection with all ones connected only in a 1000-1000-1100-0111 pattern in any orientation.at n=15A147100