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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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Andrew Howroyd, Table of n, a(n) for n = 0..100 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: A223818 A208349 A121292 * A258796 A232364 A264562 Adjacent sequences:  A208301 A208302 A208303 * A208305 A208306 A208307 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

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Last modified January 17 17:33 EST 2021. Contains 340247 sequences. (Running on oeis4.)