Number of n X n 0..3 arrays with exactly floor(n X n/2) elements unequal to at least one horizontal or antidiagonal neighbor, with new values introduced in row major 0..3 order.

A222787

Number of n X n 0..3 arrays with exactly floor(n X n/2) elements unequal to at least one horizontal or antidiagonal neighbor, with new values introduced in row major 0..3 order.