A208865 Number of n X n 0..3 arrays with new values 0..3 introduced in row major order and no element equal to more than one of its immediate leftward or upward or right-upward antidiagonal neighbors.
1, 12, 6520, 52947540, 5134914951163, 5935974611645510227, 81798476241280856702695038, 13436627707296496011221331402032076, 26310300796694291418752809230234516335649298
Offset: 1
Keywords
Examples
Some solutions for n=4 ..0..1..0..0....0..0..0..1....0..0..0..0....0..1..1..1....0..0..0..1 ..2..0..3..0....1..1..2..0....1..1..1..2....0..0..0..1....1..2..2..0 ..2..0..3..1....0..1..1..3....2..0..1..3....1..1..0..0....1..3..1..3 ..1..2..0..2....3..0..3..1....1..3..0..1....0..1..1..1....1..0..3..0
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