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A223242 3-loop graph coloring a rectangular array: number of n X 3 0..6 arrays where 0..6 label nodes of a graph with edges 0,1 1,2 2,0 0,3 3,4 4,0 0,5 5,6 6,0 and every array movement to a horizontal or vertical neighbor moves along an edge of this graph. 1
60, 642, 11538, 144582, 2663082, 33590454, 616998282, 7808992566, 142965076362, 1815370659126, 33127391927562, 422008111094454, 7676351980853898, 98098336800910134, 1778822826035815434, 22802798712088642998 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 3 of A223247.

LINKS

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

FORMULA

Empirical: a(n) = 2*a(n-1) + 231*a(n-2) - 430*a(n-3) - 286*a(n-4) + 180*a(n-5).

Empirical g.f.: 6*x*(10 + 87*x - 601*x^2 - 166*x^3 + 310*x^4) / (1 - 2*x - 231*x^2 + 430*x^3 + 286*x^4 - 180*x^5). - Colin Barker, Aug 17 2018

EXAMPLE

Some solutions for n=3:

..4..0..3....5..6..0....3..0..2....1..0..6....4..0..2....5..0..3....3..0..6

..0..1..0....6..5..6....0..5..0....0..1..0....0..6..0....0..4..0....0..4..0

..3..0..5....5..0..5....5..6..5....6..0..1....2..0..5....1..0..6....3..0..1

CROSSREFS

Cf. A223247.

Sequence in context: A283786 A099344 A324068 * A244837 A268624 A088945

Adjacent sequences:  A223239 A223240 A223241 * A223243 A223244 A223245

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 18 2013

STATUS

approved

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Last modified January 24 07:18 EST 2020. Contains 331189 sequences. (Running on oeis4.)