Number of (n+1)X(n+1) -11..11 symmetric matrices with every 2X2 subblock having sum zero and two, three or four distinct values.
A211718
Number of (n+1)X(n+1) -11..11 symmetric matrices with every 2X2 subblock having sum zero and two, three or four distinct values.
Terms
- a(0) =264a(1) =3038a(2) =35014a(3) =404214a(4) =4673910a(5) =54129486a(6) =627846218a(7) =7293174926a(8) =84839745786a(9) =988267636274
External references
- oeis: A211718