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A269092 Number of n X 3 0..3 arrays with some element plus some horizontally or vertically adjacent neighbor totalling three exactly once. 1
24, 1152, 31296, 715320, 15024096, 300056400, 5795398368, 109294975080, 2024660774592, 36988673403168, 668280340085760, 11964667932759960, 212595089870143008, 3753382504394332656, 65903307050002080672 (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) = 36*a(n-1) - 378*a(n-2) + 972*a(n-3) - 729*a(n-4) for n>5.

Empirical g.f.: 24*x*(1 + 12*x - 46*x^2 + 33*x^3 + 9*x^4) / (1 - 18*x + 27*x^2)^2. - Colin Barker, Jan 19 2019

EXAMPLE

Some solutions for n=3:

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

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

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

CROSSREFS

Column 3 of A269097.

Sequence in context: A160260 A268149 A114051 * A010562 A080775 A191744

Adjacent sequences: A269089 A269090 A269091 * A269093 A269094 A269095

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 19 2016

STATUS

approved

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Last modified December 1 21:09 EST 2022. Contains 358484 sequences. (Running on oeis4.)