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A233165 Number of n X 5 0..7 arrays with no element x(i,j) adjacent to itself or value 7-x(i,j) horizontally, diagonally, antidiagonally or vertically, top left element zero, and 1 appearing before 2 3 4 5 and 6, 2 appearing before 3 4 and 5, and 3 appearing before 4 in row major order (unlabelled 8-colorings with no clashing color pairs). 1
48, 512, 18432, 720896, 31457280, 1543503872, 83751862272, 4879082848256, 296868139499520, 18506979718725632, 1168684103302643712, 74291379453103702016, 4738507383934141071360, 302747963737721161121792 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 96*a(n-1) - 2048*a(n-2) for n>3.
Conjectures from Colin Barker, Oct 09 2018: (Start)
G.f.: 16*x*(3 - 256*x + 4224*x^2) / ((1 - 32*x)*(1 - 64*x)).
a(n) = 2^(5*n-6) * (2^n+28) for n>1.
(End)
EXAMPLE
Some solutions for n=3:
..0..1..7..2..7....0..1..7..6..2....0..1..2..3..2....0..1..2..1..2
..3..2..3..6..4....5..3..2..3..0....2..3..7..1..7....2..3..7..3..7
..0..6..7..2..0....0..6..7..6..5....7..6..2..3..5....0..6..5..1..2
CROSSREFS
Column 5 of A233168.
Sequence in context: A211149 A034778 A060674 * A247743 A189346 A334713
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 05 2013
STATUS
approved

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Last modified October 2 22:30 EDT 2023. Contains 365841 sequences. (Running on oeis4.)