1/4 the number of n X n 0..3 symmetric matrices with every element equal to zero, two or four horizontal and vertical neighbors.
A211088
1/4 the number of n X n 0..3 symmetric matrices with every element equal to zero, two or four horizontal and vertical neighbors.
Terms
- a(0) =1a(1) =10a(2) =240a(3) =13872a(4) =1924416a(5) =641053824a(6) =512493408768
External references
- oeis: A211088