A233176 Number of 3 X n 0..5 arrays with no element x(i,j) adjacent to itself or value 5-x(i,j) horizontally, diagonally or antidiagonally, top left element zero, and 1 appearing before 2 3 and 4, and 2 appearing before 3 in row major order (unlabelled 6-colorings with no clashing color pairs).

11, 80, 2688, 78336, 2469888, 76447744, 2385772544, 74291609600, 2315406802944, 72144847372288, 2248141575290880, 70053467808333824, 2182930872087347200, 68021929516908675072, 2119621843032249204736, 66049216835347669843968

Offset

1,1

Links

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

Formula

Empirical: a(n) = 32*a(n-1) + 64*a(n-2) - 3072*a(n-3) + 8192*a(n-4) for n>5.

Empirical g.f.: x*(11 - 272*x - 576*x^2 + 20992*x^3 - 53248*x^4) / ((1 - 8*x)*(1 - 24*x - 256*x^2 + 1024*x^3)). - Colin Barker, Oct 10 2018

Example

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

Crossrefs

Row 3 of A233174.

Sequence in context: A091098 A091115 A024146 * A156847 A119364 A305826

Adjacent sequences: A233173 A233174 A233175 * A233177 A233178 A233179

Keyword

nonn

Author

R. H. Hardin, Dec 05 2013

Status

approved