A206686 Number of n X n 0..3 arrays with no element equal to another within two positions in the same row or column, and new values 0..3 introduced in row major order

1, 4, 44, 916, 31504, 1915580, 208563912, 41832855136, 15644344542416, 10971573350181154

Offset

1,2

Comments

Diagonal of A206692

Links

Table of n, a(n) for n=1..10.

Example

Some solutions for n=4
..0..1..2..0....0..1..2..3....0..1..2..3....0..1..2..3....0..1..2..3
..2..0..1..2....1..0..3..1....3..2..0..1....1..2..0..1....1..3..0..1
..1..3..0..1....2..3..1..0....1..0..3..2....2..3..1..0....3..0..1..2
..3..1..2..3....0..1..2..3....2..3..1..0....0..1..2..3....2..1..3..0

Crossrefs

Sequence in context: A144004 A240318 A227656 * A302909 A053333 A301942

Adjacent sequences: A206683 A206684 A206685 * A206687 A206688 A206689

Keyword

nonn

Author

R. H. Hardin Feb 11 2012

Status

approved