Number of (n+1) X (n+1) -3..3 symmetric matrices with every 2 X 2 subblock having sum zero and two, three or four distinct values.
A211328
Number of (n+1) X (n+1) -3..3 symmetric matrices with every 2 X 2 subblock having sum zero and two, three or four distinct values.
Terms
- a(0) =24a(1) =86a(2) =310a(3) =1134a(4) =4190a(5) =15582a(6) =58130a(7) =217014a(8) =809418a(9) =3013130a(10) =11188738a(11) =41433570a(12) =153004862a(13) =563461506a(14) =2069583806a(15) =7582810302a(16) =27719202126a(17) =101113824446a(18) =368123385634
External references
- oeis: A211328