Number of n X n 0..3 arrays with every element neighboring horizontally or vertically both a 0 and a 1, and 2 introduced before 3 in row major order.

A204294

Number of n X n 0..3 arrays with every element neighboring horizontally or vertically both a 0 and a 1, and 2 introduced before 3 in row major order.

Terms

    a(0) =0a(1) =4a(2) =80a(3) =5956a(4) =6709692a(5) =47309058644

External references