Number of (n+1) X (n+1) -3..3 symmetric matrices with every 2 X 2 subblock having sum zero and two or three distinct values.
A211325
Number of (n+1) X (n+1) -3..3 symmetric matrices with every 2 X 2 subblock having sum zero and two or three distinct values.
Terms
- a(0) =24a(1) =58a(2) =126a(3) =274a(4) =572a(5) =1202a(6) =2470a(7) =5118a(8) =10466a(9) =21560a(10) =44066a(11) =90582a(12) =185338a(13) =380818a(14) =780392a(15) =1604082a(16) =3292390a(17) =6772414a(18) =13921038a(19) =28660928a(20) =58993382a(21) =121571918a(22) =250540314a(23) =516800746a(24) =1066237980a(25) =2201452066a(26) =4546640338a(27) =9396025014
External references
- oeis: A211325