Number of (n+1) X (n+1) -3..3 symmetric matrices with every 2 X 2 subblock having sum zero and one, two or three distinct values.
A211326
Number of (n+1) X (n+1) -3..3 symmetric matrices with every 2 X 2 subblock having sum zero and one, two or three distinct values.
Terms
- a(0) =25a(1) =63a(2) =149a(3) =357a(4) =829a(5) =1941a(6) =4479a(7) =10413a(8) =24087a(9) =56079a(10) =130523a(11) =305431a(12) =715961a(13) =1685595a(14) =3977689a(15) =9418701a(16) =22352933a(17) =53188057a(18) =126803131a(19) =302898825a(20) =724648975a(21) =1736139523a(22) =4164319291a(23) =9999028263a(24) =24029343133a(25) =57789827919a(26) =139068433021
External references
- oeis: A211326