A199239 Number of n X n 0..2 arrays with values 0..2 introduced in row major order, the number of instances of each value within one of each other, and every element equal to zero or two horizontal or vertical neighbors.
1, 2, 6, 440, 29227, 1682457, 2013526831
Offset: 1
Keywords
Examples
Some solutions for n=4 ..0..1..0..1....0..1..1..2....0..1..0..2....0..1..1..0....0..1..0..1 ..1..2..2..0....2..1..1..0....2..0..2..1....2..1..1..2....1..0..2..0 ..0..2..2..1....0..2..0..2....1..2..1..0....1..0..2..0....0..2..0..2 ..2..1..0..2....2..1..2..0....2..0..2..1....0..2..0..2....2..1..2..1
Comments