Number of n X n symmetric 0..4 arrays with each element equal to at least one horizontal or vertical neighbor and any new values 0..4 introduced in lower triangular row major order.

A192641

Number of n X n symmetric 0..4 arrays with each element equal to at least one horizontal or vertical neighbor and any new values 0..4 introduced in lower triangular row major order.

Terms

    a(0) =0a(1) =1a(2) =5a(3) =137a(4) =17487a(5) =11679460a(6) =29893061411

External references