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A223250 Two-loop graph coloring a rectangular array: number of n X 3 0..4 arrays where 0..4 label nodes of a graph with edges 0,1 1,2 2,0 0,3 3,4 4,0 and every array movement to a horizontal or vertical neighbor moves along an edge of this graph. 1
32, 236, 2172, 17828, 166892, 1382228, 12894316, 107283636, 996653548, 8326150836, 77047324460, 646086687220, 5957011569772, 50127570610868, 460630428892844, 3888717399278196, 35622664419652844, 301636706357260340 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 3 of A223255.

LINKS

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

FORMULA

Empirical: a(n) = 2*a(n-1) +75*a(n-2) -126*a(n-3) -70*a(n-4) +48*a(n-5).

Empirical g.f.: -4*x*(78*x^4 -46*x^3 -175*x^2 +43*x +8) / (48*x^5 -70*x^4 -126*x^3 +75*x^2 +2*x -1). - Colin Barker, May 03 2014

EXAMPLE

Some solutions for n=3:

..3..0..1....4..0..3....3..4..3....1..0..4....4..3..4....1..0..3....1..0..3

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

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

CROSSREFS

Sequence in context: A301889 A302085 A229400 * A250748 A060622 A118999

Adjacent sequences:  A223247 A223248 A223249 * A223251 A223252 A223253

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 18 2013

STATUS

approved

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Last modified October 22 22:34 EDT 2019. Contains 328335 sequences. (Running on oeis4.)