A269209 Number of n X 3 0..3 arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling three exactly once.

24, 768, 18048, 361728, 6712704, 118872576, 2039727744, 34214296320, 564168820608, 9179147971584, 147751571802240, 2357407757843712, 37337046775523712, 587670598254177792, 9200252201653201536

Offset

1,1

Links

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

Formula

Empirical: a(n) = 30*a(n-1) - 237*a(n-2) + 180*a(n-3) - 36*a(n-4) for n>5.

Empirical g.f.: 24*x*(1 + 2*x + 29*x^2 - 84*x^3 + 36*x^4) / (1 - 15*x + 6*x^2)^2. - Colin Barker, Jan 20 2019

Example

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

Crossrefs

Column 3 of A269214.

Sequence in context: A359480 A361661 A269147 * A270252 A275635 A158651

Adjacent sequences: A269206 A269207 A269208 * A269210 A269211 A269212

Keyword

nonn

Author

R. H. Hardin, Feb 20 2016

Status

approved