Number of (n+1) X (n+1) -3..3 symmetric matrices with every 2 X 2 subblock having sum zero and three distinct values.
A211323
Number of (n+1) X (n+1) -3..3 symmetric matrices with every 2 X 2 subblock having sum zero and three distinct values.
Terms
- a(0) =14a(1) =24a(2) =42a(3) =76a(4) =140a(5) =262a(6) =496a(7) =948a(8) =1826a(9) =3540a(10) =6900a(11) =13510a(12) =26552a(13) =52348a(14) =103474a(15) =204972a(16) =406748a(17) =808326a(18) =1608288a(19) =3203044a(20) =6384194a(21) =12732964a(22) =25408612a(23) =50724486a(24) =101298920a(25) =202355052a(26) =404317266a(27) =807998908a(28) =1614969356a(29) =3228274630
External references
- oeis: A211323