A233107 Number of n X 2 0..5 arrays with no element x(i,j) adjacent to value 5-x(i,j) horizontally or vertically, top left element zero, and 1 appearing before 2 3 and 4, and 2 appearing before 3 in row major order.

2, 19, 313, 6046, 123352, 2565169, 53692063, 1126297996, 23643610702, 496455294319, 10425137467813, 218924920833946, 4597402575582052, 96545308753707469, 2027450466493247563, 42576452675015933896

Offset

1,1

Comments

Column 2 of A233113.

Links

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

Formula

Empirical: a(n) = 29*a(n-1) - 175*a(n-2) + 147*a(n-3).

Conjectures from Colin Barker, Mar 19 2018: (Start)

G.f.: x*(2 - 7*x)*(1 - 16*x) / ((1 - x)*(1 - 7*x)*(1 - 21*x)).

a(n) = (105 + 18*7^n + 5*21^n) / 168.

(End)

Example

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

Crossrefs

Cf. A233113.

Sequence in context: A304637 A119773 A137647 * A187659 A308330 A078369

Adjacent sequences: A233104 A233105 A233106 * A233108 A233109 A233110

Keyword

nonn

Author

R. H. Hardin, Dec 04 2013

Status

approved