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A233164 Number of n X 4 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
11, 64, 1280, 28672, 720896, 19922944, 587202560, 17985175552, 562640715776, 17798344474624, 566248488304640, 18067175067615232, 577305177233555456, 18460254872591663104, 590511983140819435520, 18892924695992401395712 (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) - 512*a(n-2) for n>3.

Conjectures from Colin Barker, Oct 09 2018: (Start)

G.f.: x*(11 - 464*x + 3840*x^2) / ((1 - 16*x)*(1 - 32*x)).

a(n) = 4^(2*n-3) * (2^n+12) for n>1.

(End)

EXAMPLE

Some solutions for n=4:

..0..1..2..1....0..1..7..1....0..1..0..1....0..1..0..1....0..1..0..2

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

..0..6..5..6....1..0..6..0....0..6..7..6....0..1..0..1....0..6..0..2

..5..3..7..4....5..4..2..4....5..3..2..3....5..4..5..4....3..5..3..6

CROSSREFS

Column 4 of A233168.

Sequence in context: A285361 A237358 A250604 * A215445 A184055 A332750

Adjacent sequences:  A233161 A233162 A233163 * A233165 A233166 A233167

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 05 2013

STATUS

approved

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Last modified December 7 06:09 EST 2021. Contains 349567 sequences. (Running on oeis4.)