A276293 Number of n X 2 0..2 arrays with no element equal to any value at offset (-2,-1) (-1,1) or (0,-1) and new values introduced in order 0..2.

1, 4, 11, 31, 88, 250, 710, 2016, 5724, 16252, 46144, 131016, 371992, 1056192, 2998832, 8514544, 24175232, 68640416, 194889824, 553348096, 1571113920, 4460842944, 12665612288, 35961305216, 102104457600, 289903834112

Offset

1,2

Links

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

Formula

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

Empirical g.f.: x*(1 - x^2 + x^3) / (1 - 4*x + 4*x^2 - 2*x^3). - Colin Barker, Feb 05 2019

Example

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

Crossrefs

Column 2 of A276299.

Sequence in context: A298300 A027115 A077995 * A282856 A296572 A176573

Adjacent sequences: A276290 A276291 A276292 * A276294 A276295 A276296

Keyword

nonn

Author

R. H. Hardin, Aug 28 2016

Status

approved