1/4 the number of n X n 0..3 symmetric matrices with every element equal to one, two, three or four horizontal and vertical neighbors.
A211094
1/4 the number of n X n 0..3 symmetric matrices with every element equal to one, two, three or four horizontal and vertical neighbors.
Terms
- a(0) =0a(1) =1a(2) =13a(3) =679a(4) =87781a(5) =35830153a(6) =43041488701
External references
- oeis: A211094