817961domain: NAppears in sequencesGeneralized Markoff numbers: union of numbers a, b, c, d satisfying the Markoff(4) equation a^2 + b^2 + c^2 + d^2 = 4*a*b*c*d.at n=23A075276Number of n X n binary arrays symmetric about main diagonal with all ones connected only in a 1100-0111-0110 pattern in any orientation.at n=12A146669