Half the number of (n+1)X(n+1) symmetric 0..2 arrays with no 2X2 subblock summing to 4.
A213691
Half the number of (n+1)X(n+1) symmetric 0..2 arrays with no 2X2 subblock summing to 4.
Terms
- a(0) =11a(1) =192a(2) =7827a(3) =750261a(4) =168382284a(5) =88681187619
External references
- oeis: A213691