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A223442 4-level binary fanout graph coloring a rectangular array: number of n X 1 0..14 arrays where 0..14 label nodes of a graph with edges 0,1 1,3 3,5 3,6 1,4 4,7 4,8 0,2 2,9 9,11 9,12 2,10 10,13 10,14 and every array movement to a horizontal or vertical neighbor moves along an edge of this graph. 1
15, 28, 66, 144, 336, 752, 1752, 3936, 9168, 20608, 48000, 107904, 251328, 564992, 1315968, 2958336, 6890496, 15490048, 36079104, 81106944, 188912640, 424681472, 989159424, 2223661056, 5179305984, 11643240448, 27119198208, 60964798464 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Column 1 of A223449.
LINKS
FORMULA
Empirical: a(n) = 6*a(n-2) - 4*a(n-4).
Empirical g.f.: x*(3 + 2*x)*(5 + 6*x - 12*x^2) / (1 - 6*x^2 + 4*x^4). - Colin Barker, Aug 20 2018
EXAMPLE
Some solutions for n=3:
.12...13....3....7....1....8....2....2....9....2....6....1....0....2...11....0
..9...10....1....4....0....4....0....9....2....0....3....0....2....9....9....2
..2...13....0....8....2....8....1...12...10....2....1....1....9...11....2....0
CROSSREFS
Cf. A223449.
Sequence in context: A350045 A357278 A343067 * A121594 A163286 A022997
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 20 2013
STATUS
approved

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Last modified February 27 14:41 EST 2024. Contains 370376 sequences. (Running on oeis4.)