1/4 the number of n X n 0..3 symmetric matrices with every element equal to zero, two or three horizontal and vertical neighbors.
A211084
1/4 the number of n X n 0..3 symmetric matrices with every element equal to zero, two or three horizontal and vertical neighbors.
Terms
- a(0) =1a(1) =10a(2) =228a(3) =13227a(4) =1888962a(5) =662705112a(6) =570731832303
External references
- oeis: A211084