Number of (n+1)X(n+1) -4..4 symmetric matrices with every 2X2 subblock having sum zero and two, three or four distinct values.
A211497
Number of (n+1)X(n+1) -4..4 symmetric matrices with every 2X2 subblock having sum zero and two, three or four distinct values.
Terms
- a(0) =40a(1) =180a(2) =808a(3) =3636a(4) =16396a(5) =74104a(6) =335660a(7) =1523420a(8) =6925768a(9) =31527492a(10) =143656108a(11) =654965928a(12) =2986993420a(13) =13622286844a(14) =62110476152a(15) =283072002980
External references
- oeis: A211497