A233240 Number of 2 X n 0..5 arrays with no element x(i,j) adjacent to 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.

3, 19, 271, 4504, 79201, 1419889, 25622596, 463384804, 8386411051, 151815188839, 2748457460746, 49759306786354, 900872721644401, 16309994546050789, 295287194569964896, 5346081195735699904, 96789118201657881751

Offset

1,1

Links

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

Formula

Empirical: a(n) = 23*a(n-1) - 81*a(n-2) - 143*a(n-3) + 82*a(n-4) + 120*a(n-5) for n>6.

Empirical g.f.: x*(3 - 50*x + 77*x^2 + 239*x^3 + 31*x^4 - 75*x^5) / ((1 - x)*(1 + x)*(1 - 6*x)*(1 - 17*x - 20*x^2)). - Colin Barker, Oct 10 2018

Example

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

Crossrefs

Row 2 of A233239.

Sequence in context: A305562 A356672 A316294 * A173799 A003011 A338772

Adjacent sequences: A233237 A233238 A233239 * A233241 A233242 A233243

Keyword

nonn

Author

R. H. Hardin, Dec 06 2013

Status

approved