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A269196 Number of n X 3 0..3 arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling three no more than once. 1
60, 1284, 25572, 471492, 8314020, 142233732, 2380537188, 39186271044, 636703584804, 10237337586180, 163189207436004, 2582623154662596, 40622651914004388, 635603382950474628, 9899530341266770020 (list; graph; refs; listen; history; text; internal format)
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.: 12*x*(1 - 6*x)*(5 - 13*x + 28*x^2 - 12*x^3) / (1 - 15*x + 6*x^2)^2. - Colin Barker, Jan 20 2019

EXAMPLE

Some solutions for n=3:

..3..1..1. .2..3..2. .3..1..0. .1..0..1. .2..0..3. .3..3..3. .3..3..3

..3..1..0. .2..2..0. .0..0..1. .1..3..2. .2..3..2. .3..1..1. .3..3..2

..0..2..3. .2..2..2. .0..1..0. .0..0..2. .3..2..2. .1..0..1. .3..2..3

CROSSREFS

Column 3 of A269201.

Sequence in context: A146347 A289156 A288960 * A054331 A160349 A281373

Adjacent sequences:  A269193 A269194 A269195 * A269197 A269198 A269199

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 20 2016

STATUS

approved

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Last modified April 22 07:26 EDT 2021. Contains 343163 sequences. (Running on oeis4.)