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Number of n X 6 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).
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%I #8 Oct 11 2018 04:42:35

%S 136,166400,220626944,294517735424,393427728465920,525597937107992576,

%T 702177183940808278016,938080982436565861007360,

%U 1253239344772433062871957504,1674278572660580852636051308544

%N Number of n X 6 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).

%H R. H. Hardin, <a href="/A233254/b233254.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 1664*a(n-1) - 471040*a(n-2) + 44826624*a(n-3) - 1358954496*a(n-4).

%F Empirical g.f.: 8*x*(17 - 7488*x + 974848*x^2 - 40108032*x^3) / ((1 - 64*x)*(1 - 1600*x + 368640*x^2 - 21233664*x^3)). - _Colin Barker_, Oct 11 2018

%e Some solutions for n=2:

%e ..0..1..2..1..2..4....0..1..0..2..1..0....0..1..2..1..0..3....0..1..2..1..3..5

%e ..5..4..0..1..0..3....0..1..5..2..1..2....0..4..5..1..0..3....3..4..3..0..4..2

%Y Column 6 of A233256.

%K nonn

%O 1,1

%A _R. H. Hardin_, Dec 06 2013