Number of (n+1)X(n+1) -6..6 symmetric matrices with every 2X2 subblock having sum zero and two, three or four distinct values.
A211260
Number of (n+1)X(n+1) -6..6 symmetric matrices with every 2X2 subblock having sum zero and two, three or four distinct values.
Terms
- a(0) =84a(1) =546a(2) =3552a(3) =23154a(4) =151218a(5) =989484a(6) =6486618a(7) =42598386a(8) =280208436a(9) =1845953430a(10) =12177085710a(11) =80422381488a(12) =531677196078
External references
- oeis: A211260