A223213 3X3X3 triangular graph coloring a rectangular array: number of nX3 0..5 arrays where 0..5 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 and every array movement to a horizontal or vertical neighbor moves along an edge of this graph

60, 918, 15498, 254694, 4232586, 70014654, 1160465118, 19217863458, 318374151654, 5273531868834, 87356475139362, 1447024166557638, 23969667617068794, 397050589780025454, 6577043474587192446

Offset

1,1

Comments

Column 3 of A223218

Links

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

Formula

Empirical: a(n) = 10*a(n-1) +118*a(n-2) -120*a(n-3) -577*a(n-4) +380*a(n-5) +504*a(n-6) -16*a(n-8).

Empirical g.f.: -6*x*(-10-53*x+127*x^2+235*x^3-277*x^4-258*x^5+4*x^6+8*x^7) / ( 1-10*x-118*x^2+120*x^3+577*x^4-380*x^5-504*x^6+16*x^8 ). - R. J. Mathar, May 21 2018

Example

Some solutions for n=3
..1..4..2....2..5..2....5..2..5....4..1..3....4..5..4....1..2..1....4..1..2
..4..5..4....5..2..1....4..1..4....2..4..1....1..4..1....2..1..4....2..4..5
..3..4..1....2..1..3....3..4..3....4..1..4....4..1..2....1..4..5....4..5..4

Crossrefs

Sequence in context: A056312 A268967 A189607 * A271651 A223348 A305545

Adjacent sequences: A223210 A223211 A223212 * A223214 A223215 A223216

Keyword

nonn

Author

R. H. Hardin Mar 18 2013

Status

approved