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A269209 Number of n X 3 0..3 arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling three exactly once. 1
24, 768, 18048, 361728, 6712704, 118872576, 2039727744, 34214296320, 564168820608, 9179147971584, 147751571802240, 2357407757843712, 37337046775523712, 587670598254177792, 9200252201653201536 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
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
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 20 2016
STATUS
approved

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Last modified March 29 09:14 EDT 2024. Contains 371268 sequences. (Running on oeis4.)