A183494 Half the number of nX1 0..2 arrays with no element equal to the sum mod 3 of its horizontal and vertical neighbors

1, 3, 4, 8, 18, 32, 64, 132, 256, 512, 1032, 2048, 4096, 8208, 16384, 32768, 65568, 131072, 262144, 524352, 1048576, 2097152, 4194432, 8388608, 16777216, 33554688, 67108864, 134217728, 268435968, 536870912, 1073741824, 2147484672, 4294967296

Offset

1,2

Comments

Column 1 of A183501

Links

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

Formula

Empirical: a(n)=2*a(n-1)+2*a(n-3)-4*a(n-4).

Empirical G.f.: x*(1+x)*(1-2*x^2)/(1-2*x)/(1-2*x^3). [Colin Barker, Feb 23 2012]

Example

All solutions for 3X1
..0....1....0....0....0....1....2....2
..2....0....1....1....2....2....1....0
..1....1....2....0....0....0....0....2

Crossrefs

Sequence in context: A153057 A215095 A192474 * A107429 A061273 A254715

Adjacent sequences: A183491 A183492 A183493 * A183495 A183496 A183497

Keyword

nonn

Author

R. H. Hardin Jan 05 2011

Status

approved