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A269284 Number of n X 3 0..3 arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling three no more than once. 1
60, 2124, 62748, 1698732, 43674876, 1085203980, 26317946844, 626778812268, 14718495557052, 341767357185996, 7863372461151900, 179542238849355564, 4073026776304945788, 91888997272241919372, 2063133077083679521116 (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) = 42*a(n-1) - 441*a(n-2).

Conjectures from Colin Barker, Jan 21 2019: (Start)

G.f.: 12*x*(5 - 33*x) / (1 - 21*x)^2.

a(n) = 4 * 3^n * 7^(n-2) * (24*n+11).

(End)

EXAMPLE

Some solutions for n=3:

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

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

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

CROSSREFS

Column 3 of A269289.

Sequence in context: A083367 A173123 A004353 * A004364 A054623 A075908

Adjacent sequences:  A269281 A269282 A269283 * A269285 A269286 A269287

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 21 2016

STATUS

approved

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Last modified September 22 19:36 EDT 2021. Contains 347608 sequences. (Running on oeis4.)