A239025 Number of n X 3 0..2 arrays with no element equal to the sum of elements to its left or one plus the sum of elements above it, modulo 3.

1, 4, 7, 28, 54, 212, 428, 1652, 3410, 13004, 27158, 102740, 215998, 812892, 1715842, 6435860, 13618366, 50970780, 108022954, 403751540, 856522206, 3198552316, 6789722794, 25340854612, 53813984430, 200773770908, 426474521338

Offset

1,2

Links

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

Formula

Empirical: a(n) = 17*a(n-2) - 96*a(n-4) + 210*a(n-6) - 152*a(n-8).

Empirical g.f.: x*(1 + 4*x - 10*x^2 - 40*x^3 + 31*x^4 + 120*x^5 - 28*x^6 - 104*x^7) / (1 - 17*x^2 + 96*x^4 - 210*x^6 + 152*x^8). - Colin Barker, Oct 25 2018

Example

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

Crossrefs

Column 3 of A239030.

Sequence in context: A146085 A359067 A061668 * A339393 A128386 A149074

Adjacent sequences: A239022 A239023 A239024 * A239026 A239027 A239028

Keyword

nonn

Author

R. H. Hardin, Mar 09 2014

Status

approved