Number of (n+1) X (n+1) -6..6 symmetric matrices with every 2 X 2 subblock having sum zero and three distinct values.
A211254
Number of (n+1) X (n+1) -6..6 symmetric matrices with every 2 X 2 subblock having sum zero and three distinct values.
Terms
- a(0) =64a(1) =130a(2) =246a(3) =456a(4) =840a(5) =1538a(6) =2830a(7) =5214a(8) =9672a(9) =18020a(10) =33790a(11) =63702a(12) =120752a(13) =230126a(14) =440512a(15) =847370a(16) =1635656a(17) =3170660a(18) =6162524a(19) =12020244a(20) =23492880a(21) =46050762a(22) =90403706a(23) =177902814a(24) =350479066a(25) =691826684a(26) =1366757298a(27) =2704492222a(28) =5354853154
External references
- oeis: A211254