Number of (n+1)X(n+1) -9..9 symmetric matrices with every 2X2 subblock having sum zero and three or four distinct values.
A211554
Number of (n+1)X(n+1) -9..9 symmetric matrices with every 2X2 subblock having sum zero and three or four distinct values.
Terms
- a(0) =150a(1) =1194a(2) =9390a(3) =73506a(4) =572242a(5) =4435846a(6) =34254414a(7) =263666834a(8) =2023872594a(9) =15497836998a(10) =118429480822a(11) =903378800274
External references
- oeis: A211554