Number of n X n symmetric binary matrices with each 1 adjacent to exactly 2 diagonally or antidiagonally neighboring 1s.
A191274
Number of n X n symmetric binary matrices with each 1 adjacent to exactly 2 diagonally or antidiagonally neighboring 1s.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =3a(4) =8a(5) =35a(6) =208a(7) =1147a(8) =10098a(9) =106904a(10) =1615656a(11) =31267328a(12) =833655362a(13) =29769092579
External references
- oeis: A191274