Number of n X n 0..4 arrays with some element plus some horizontally or vertically adjacent neighbor totalling four exactly once.
A270051
Number of n X n 0..4 arrays with some element plus some horizontally or vertically adjacent neighbor totalling four exactly once.
Terms
- a(0) =0a(1) =240a(2) =385200a(3) =4410058320
External references
- oeis: A270051