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A208304
Number of 4 X n nonnegative integer arrays with new values 0 upwards introduced in row major order and no element equal to any horizontal or antidiagonal neighbor (colorings ignoring permutations of colors).
1
1, 15, 877, 433252, 656404264, 2227156082842, 14216420563705724, 152834703739876070716, 2562708954761302163168116, 63338792205478132108785337770, 2209363673047740561377241754826088, 105080298194482216982100203776114994146, 6626004995903793205763315247117544349120572
OFFSET
0,2
LINKS
EXAMPLE
Some solutions for n=4:
..0..1..0..1....0..1..0..1....0..1..0..1....0..1..0..1....0..1..0..1
..0..1..2..0....0..1..0..1....0..1..0..1....0..1..0..1....0..1..0..2
..0..1..2..0....0..1..0..1....0..1..0..1....2..1..0..1....2..1..0..1
..0..1..2..0....2..1..0..1....0..1..0..1....0..1..0..1....0..1..0..2
CROSSREFS
Row 4 of A208301.
Sequence in context: A208349 A358802 A121292 * A258796 A232364 A264562
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 25 2012
EXTENSIONS
a(0)=1 prepended and terms a(8) and beyond from Andrew Howroyd, May 18 2020
STATUS
approved