Equals two maps: number of nX4 binary arrays indicating the locations of corresponding elements equal to exactly two of their horizontal, vertical and antidiagonal neighbors in a random 0..3 nX4 array.

A220531

Equals two maps: number of nX4 binary arrays indicating the locations of corresponding elements equal to exactly two of their horizontal, vertical and antidiagonal neighbors in a random 0..3 nX4 array.

Terms

    a(0) =4a(1) =107a(2) =2660a(3) =53150a(4) =947486a(5) =15864668a(6) =258344332a(7) =4160105184

External references