Number of (n+1) X (n+1) -4..4 symmetric matrices with every 2 X 2 subblock having sum zero and three or four distinct values.
A211495
Number of (n+1) X (n+1) -4..4 symmetric matrices with every 2 X 2 subblock having sum zero and three or four distinct values.
Terms
- a(0) =28a(1) =96a(2) =336a(3) =1208a(4) =4360a(5) =15792a(6) =57128a(7) =206424a(8) =744656a(9) =2682848a(10) =9656216a(11) =34733096a(12) =124894432a(13) =449073872a(14) =1614961224a(15) =5809590552a(16) =20908485840a(17) =75288818816a(18) =271266031480a(19) =977986031752
External references
- oeis: A211495