A233252 - OEIS

A233252

Number of n X 4 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).

10, 1184, 166400, 23896064, 3439984640, 495341010944, 71328837140480, 10271348253261824, 1479074079750225920, 212986666384520904704, 30670079941778824232960, 4416491511334675712835584

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OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = 160*a(n-1) - 2304*a(n-2).

Conjectures from Colin Barker, Oct 10 2018: (Start)

G.f.: 2*x*(5 - 208*x) / ((1 - 16*x)*(1 - 144*x)).

a(n) = 2^(4*n-3) * (4*9^n+9) / 9.

(End)

EXAMPLE

Some solutions for n=2:

..0..1..2..1....0..1..0..1....0..1..2..4....0..1..0..1....0..1..2..4

..0..1..3..0....0..2..5..3....3..1..5..4....5..2..5..3....3..4..5..3

CROSSREFS

Column 4 of A233256.

Sequence in context: A266621 A110731 A223119 * A249849 A027879 A194497

Adjacent sequences: A233249 A233250 A233251 * A233253 A233254 A233255

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 06 2013

STATUS

approved