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).

48, 512, 18432, 720896, 31457280, 1543503872, 83751862272, 4879082848256, 296868139499520, 18506979718725632, 1168684103302643712, 74291379453103702016, 4738507383934141071360, 302747963737721161121792

Offset: 1

Author

R. H. Hardin, Dec 05 2013

Keywords

• nonn

Examples

			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
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210

Crossrefs

Column 5 of A233168.

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)