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A223338
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.
1
60, 612, 6696, 74736, 840456, 9474840, 106904016, 1206530100, 13618313028, 153717108696, 1735104803220, 19585324103616, 221073319268820, 2495410941230244, 28167472321321608, 317946242671782120
OFFSET
1,1
COMMENTS
Column 2 of A223344.
LINKS
FORMULA
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
EXAMPLE
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
CROSSREFS
Cf. A223344.
Sequence in context: A184191 A101384 A229750 * A081384 A283786 A099344
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 19 2013
STATUS
approved