Number of (n+1)X(n+1) -11..11 symmetric matrices with every 2X2 subblock having sum zero and one, three or four distinct values.
A211717
Number of (n+1)X(n+1) -11..11 symmetric matrices with every 2X2 subblock having sum zero and one, three or four distinct values.
Terms
- a(0) =231a(1) =2333a(2) =23349a(3) =232503a(4) =2302953a(5) =22704347a(6) =222873481a(7) =2179177539a(8) =21229916021a(9) =206133137263
External references
- oeis: A211717