A223293 4-loop graph coloring a rectangular array: number of nX4 0..8 arrays where 0..8 label nodes of a graph with edges 0,1 1,2 2,0 0,3 3,4 4,0 0,5 5,6 6,0 0,7 7,8 8,0 and every array movement to a horizontal or vertical neighbor moves along an edge of this graph

288, 11304, 709320, 46008720, 2997483624, 195340203144, 12730353920784, 829641130218216, 54067983864017544, 3523628257995013776, 229636010734298222184, 14965454234179949675400, 975303567250780213199376

Offset

1,1

Comments

Column 4 of A223297

Links

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

Formula

Empirical: a(n) = 68*a(n-1) -156*a(n-2) -1911*a(n-3) +3816*a(n-4) +3960*a(n-5) -4572*a(n-6) for n>7

Example

Some solutions for n=3
..0..1..0..3....0..3..0..8....1..0..5..0....1..0..3..4....0..1..0..3
..1..0..3..0....1..0..7..0....0..6..0..4....0..1..0..3....1..0..8..0
..0..1..0..6....0..7..0..2....2..0..7..0....2..0..8..0....0..4..0..3

Crossrefs

Sequence in context: A264001 A168555 A163731 * A035749 A048145 A022154

Adjacent sequences: A223290 A223291 A223292 * A223294 A223295 A223296

Keyword

nonn

Author

R. H. Hardin Mar 19 2013

Status

approved