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A223338
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5 X 5 X 5 triangular graph coloring a rectangular array: number of n X 2 0..14 arrays where 0..14 label nodes of a graph with edges 0,1 0,2 1,2 1,3 1,4 2,4 3,4 2,5 4,5 3,6 3,7 4,7 6,7 4,8 5,8 7,8 5,9 8,9 6,10 6,11 7,11 10,11 7,12 8,12 11,12 11,12 8,13 9,13 12,13 9,14 13,14 and every array movement to a horizontal or vertical neighbor moves along an edge of this graph.
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1
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60, 612, 6696, 74736, 840456, 9474840, 106904016, 1206530100, 13618313028, 153717108696, 1735104803220, 19585324103616, 221073319268820, 2495410941230244, 28167472321321608, 317946242671782120
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OFFSET
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1,1
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COMMENTS
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Column 2 of A223344.
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LINKS
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R. H. Hardin, Table of n, a(n) for n = 1..210
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FORMULA
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Empirical: a(n) = 13*a(n-1) - 11*a(n-2) - 94*a(n-3) - 7*a(n-4) + 79*a(n-5) - 3*a(n-6).
Empirical g.f.: 12*x*(5 - 14*x - 50*x^2 + 5*x^3 + 41*x^4 - 2*x^5) / (1 - 13*x + 11*x^2 + 94*x^3 + 7*x^4 - 79*x^5 + 3*x^6). - Colin Barker, Aug 19 2018
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EXAMPLE
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Some solutions for n=3:
..4..3....4..3...12.13....3..7...13.14....7..4....4..1....8..7....8..4....8..9
..3..6....8..7....8.12....7..3...14..9....8..7....5..4....5..4....4..5....4..5
..6..3....4..3....5..8....3..7....9..5....4..3....4..2....9..8....5..9....3..4
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CROSSREFS
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Cf. A223344.
Sequence in context: A184191 A101384 A229750 * A081384 A283786 A099344
Adjacent sequences: A223335 A223336 A223337 * A223339 A223340 A223341
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KEYWORD
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nonn
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AUTHOR
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R. H. Hardin, Mar 19 2013
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STATUS
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approved
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