63483domain: NAppears in sequencesa(n) = T(2*n+1,n+2), T given by A026998.at n=8A027005T(n,n+3), T given by A027960.at n=16A027963a(n) = 441*n^2 - 21.at n=11A145678144*n^2 - n.at n=20A156635Number of (n+1) X (n+1) -2..2 symmetric matrices with every 2 X 2 subblock having sum zero and one, two or three distinct values.at n=10A211116