Number of (n+1)X(n+1) -5..5 symmetric matrices with every 2X2 subblock having sum zero and two, three or four distinct values.
A211336
Number of (n+1)X(n+1) -5..5 symmetric matrices with every 2X2 subblock having sum zero and two, three or four distinct values.
Terms
- a(0) =60a(1) =332a(2) =1846a(3) =10332a(4) =58164a(5) =329130a(6) =1870664a(7) =10670876a(8) =61044918a(9) =349974788a(10) =2009495068a(11) =11549465226a(12) =66414142512a(13) =381959562756
External references
- oeis: A211336