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A223418 3-level binary fanout 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 1,3 1,4 0,2 2,5 2,6 and every array movement to a horizontal or vertical neighbor moves along an edge of this graph. 1
26, 136, 868, 4720, 29912, 163168, 1033328, 5638336, 35704800, 194827648, 1233740224, 6732071680, 42630619008, 232619832832, 1473057249024, 8037939530752, 50899980869120, 277742748522496, 1758796582951936 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 3 of A223423.

LINKS

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

FORMULA

Empirical: a(n) = 38*a(n-2) - 120*a(n-4) + 32*a(n-6).

Empirical g.f.: 2*x*(13 + 68*x - 60*x^2 - 224*x^3 + 24*x^4 + 64*x^5) / (1 - 38*x^2 + 120*x^4 - 32*x^6). - Colin Barker, Aug 20 2018

EXAMPLE

Some solutions for n=3.

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

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

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

CROSSREFS

Cf. A223423.

Sequence in context: A264287 A166801 A255019 * A331458 A238917 A200449

Adjacent sequences:  A223415 A223416 A223417 * A223419 A223420 A223421

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 20 2013

STATUS

approved

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Last modified October 25 21:15 EDT 2021. Contains 348256 sequences. (Running on oeis4.)