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 A233258 Number of 3 X n 0..5 arrays with no element x(i,j) adjacent to itself or value 5-x(i,j) horizontally or antidiagonally, top left element zero, and 1 appearing before 2 3 and 4, and 2 appearing before 3 in row major order (unlabelled 6-colorings with no clashing color pairs). 1
 11, 136, 4672, 166400, 6049792, 220626944, 8050180096, 293762760704, 10720053821440, 391200251052032, 14275841005453312, 520959990903603200, 19011091850007150592, 693760794065113186304, 25317011997007519154176 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 48*a(n-1) - 448*a(n-2) + 1024*a(n-3) for n>5. Empirical g.f.: x*(11 - 392*x + 3072*x^2 - 8192*x^3 + 16384*x^4) / ((1 - 8*x)*(1 - 40*x + 128*x^2)). - Colin Barker, Oct 11 2018 EXAMPLE Some solutions for n=3: ..0..1..5....0..1..5....0..1..2....0..1..2....0..1..2....0..1..2....0..1..2 ..5..2..5....5..2..0....3..1..3....0..4..5....2..5..3....3..1..5....5..1..2 ..1..3..5....4..2..0....5..1..2....0..2..4....1..0..2....5..4..3....5..4..0 CROSSREFS Row 3 of A233256. Sequence in context: A024143 A057718 A123800 * A262382 A142895 A232180 Adjacent sequences:  A233255 A233256 A233257 * A233259 A233260 A233261 KEYWORD nonn AUTHOR R. H. Hardin, Dec 06 2013 STATUS approved

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Last modified September 28 17:43 EDT 2020. Contains 337393 sequences. (Running on oeis4.)