A223347 3 X 3 X 3 triangular graph without horizontal edges coloring a rectangular array: number of n X 3 0..5 arrays where 0..5 label nodes of a graph with edges 0,1 0,2 1,3 1,4 2,4 2,5 and every array movement to a horizontal or vertical neighbor moves along an edge of this graph.

28, 236, 2280, 20836, 202264, 1851020, 17970056, 164457412, 1596586328, 14611562156, 141852049992, 1298194798372, 12603142057880, 115340831992268, 1119752515193608, 10247697449986948, 99486754138704856, 910478112673392620

Offset

1,1

Comments

Column 3 of A223352.

Links

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

Formula

Empirical: a(n) = 91*a(n-2) - 192*a(n-4) + 64*a(n-6).

Empirical g.f.: 4*x*(7 + 59*x - 67*x^2 - 160*x^3 + 40*x^4 + 64*x^5) / (1 - 91*x^2 + 192*x^4 - 64*x^6). - Colin Barker, Aug 19 2018

Example

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

Crossrefs

Cf. A223352.

Sequence in context: A135497 A138405 A024015 * A242436 A119544 A112797

Adjacent sequences: A223344 A223345 A223346 * A223348 A223349 A223350

Keyword

nonn

Author

R. H. Hardin, Mar 19 2013

Status

approved