A183495 Half the number of n X 2 0..2 arrays with no element equal to the sum mod 3 of its horizontal and vertical neighbors.

3, 9, 36, 128, 540, 2048, 8256, 32784, 131328, 524288, 2098368, 8388608, 33558528, 134217984, 536887296, 2147483648, 8590003200, 34359738368, 137439215616, 549755817984, 2199024304128, 8796093022208, 35184376332288, 140737488355328

Offset

1,1

Comments

Column 2 of A183501.

Links

R. H. Hardin, Table of n, a(n) for n = 1..200

Formula

Empirical: a(n) = 4*a(n-1) + 4*a(n-2) - 16*a(n-3) + 16*a(n-6) - 64*a(n-7) - 64*a(n-8) + 256*a(n-9)

Empirical g.f.: x*(3 - 3*x - 12*x^2 - 4*x^3 + 28*x^4 - 48*x^5 - 96*x^6 + 256*x^7 + 128*x^8) / ((1 - 2*x)*(1 + 2*x)*(1 - 4*x)*(1 - 4*x^3)*(1 + 4*x^3)). - Colin Barker, Mar 29 2018

Example

Some solutions for 3 X 2:
..0..2....1..0....2..0....1..1....2..1....1..1....2..0....0..0....0..0....1..2
..2..1....2..1....0..0....1..1....0..0....1..2....0..0....1..2....1..1....0..0
..0..2....2..1....0..2....1..1....2..0....2..2....2..1....1..2....2..2....1..2

Crossrefs

Cf. A183501.

Sequence in context: A149020 A187980 A057390 * A185162 A106435 A276368

Adjacent sequences: A183492 A183493 A183494 * A183496 A183497 A183498

Keyword

nonn

Author

R. H. Hardin, Jan 05 2011

Status

approved