1/3 the number of n X n 0..2 symmetric matrices with every element equal to two or three horizontal and vertical neighbors.
A211041
1/3 the number of n X n 0..2 symmetric matrices with every element equal to two or three horizontal and vertical neighbors.
Terms
- a(0) =0a(1) =1a(2) =0a(3) =6a(4) =8a(5) =118a(6) =880a(7) =14400a(8) =318220a(9) =10446298a(10) =531060152a(11) =39577654480
External references
- oeis: A211041