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A223693
Petersen graph (8,2) coloring a rectangular array: number of 2 X n 0..15 arrays where 0..15 label nodes of a graph with edges 0,1 0,8 8,14 8,10 1,2 1,9 9,15 9,11 2,3 2,10 10,12 3,4 3,11 11,13 4,5 4,12 12,14 5,6 5,13 13,15 6,7 6,14 7,0 7,15 and every array movement to a horizontal or antidiagonal neighbor moves along an edge of this graph.
1
256, 432, 2304, 12384, 66816, 361440, 1958400, 10622304, 57652992, 313044192, 1700213760, 9235776096, 50175150336, 272604245472, 1481134892544, 8047630034784, 43726888532736, 237593019598560, 1290986302371840
OFFSET
1,1
COMMENTS
Row 2 of A223692.
LINKS
FORMULA
Empirical: a(n) = 8*a(n-1) - 11*a(n-2) - 16*a(n-3) for n>4.
Empirical g.f.: 16*x*(16 - 101*x + 104*x^2 + 175*x^3) / (1 - 8*x + 11*x^2 + 16*x^3). - Colin Barker, Aug 22 2018
EXAMPLE
Some solutions for n=3:
..2.10..2....6.14.12....6..7..0...13.11..3....4..5..6....1..9..1...11.13..5
..2..3.11....8.10..2....6..7..0....3.11.13....4..5.13....1..0..8....5..4..3
CROSSREFS
Cf. A223692.
Sequence in context: A115176 A299156 A221259 * A223064 A206206 A206199
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 25 2013
STATUS
approved