A223419 3-level binary fanout graph coloring a rectangular array: number of n X 4 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.

48, 464, 4720, 47872, 486016, 4934272, 50097024, 508632832, 5164146176, 52431620096, 532338988032, 5404846559232, 54875501465600, 557151943860224, 5656773689024512, 57433325141737472, 583121585796284416

Offset: 1

Author

R. H. Hardin, Mar 20 2013

Keywords

• nonn

Comments

Column 4 of A223423.

Examples

			Some solutions for n=3:
..0..2..0..2....5..2..0..1....3..1..0..1....1..3..1..3....3..1..0..2
..1..0..1..0....2..0..1..0....1..0..1..0....0..1..4..1....1..0..1..0
..4..1..4..1....6..2..0..2....0..1..0..2....1..0..1..4....3..1..4..1
		

Links

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

Crossrefs

Cf. A223423.

Formula

Empirical: a(n) = 14*a(n-1) - 36*a(n-2) - 40*a(n-3) + 88*a(n-4) + 32*a(n-5) - 32*a(n-6).

Empirical g.f.: 16*x*(3 - 13*x - 3*x^2 + 26*x^3 + 4*x^4 - 8*x^5) / (1 - 14*x + 36*x^2 + 40*x^3 - 88*x^4 - 32*x^5 + 32*x^6). - Colin Barker, Aug 20 2018