Number of (n+1)X(n+1) -8..8 symmetric matrices with every 2X2 subblock having sum zero and one or three distinct values.
A211468
Number of (n+1)X(n+1) -8..8 symmetric matrices with every 2X2 subblock having sum zero and one or three distinct values.
Terms
- a(0) =121a(1) =277a(2) =565a(3) =1101a(4) =2135a(5) =4047a(6) =7739a(7) =14661a(8) =28031a(9) =53463a(10) =102733a(11) =197579a(12) =382143a(13) =740723a(14) =1441747a(15) =2813157a(16) =5505551a(17) =10799509a(18) =21229339a(19) =41813647a(20) =82481877a(21) =162964213a(22) =322323737a(23) =638333051a(24) =1265124641a(25) =2509927951a(26) =4982252633
External references
- oeis: A211468