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.

26, 136, 868, 4720, 29912, 163168, 1033328, 5638336, 35704800, 194827648, 1233740224, 6732071680, 42630619008, 232619832832, 1473057249024, 8037939530752, 50899980869120, 277742748522496, 1758796582951936

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