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A269054 Number of 3 X n 0..2 arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling two not more than once. 1
27, 174, 594, 3078, 13140, 58752, 253416, 1090344, 4637904, 19604352, 82332384, 343986912, 1430547456, 5925418752, 24456120000, 100618925568, 412797979584, 1689208728576, 6896384506176, 28095875422848, 114241910041536 (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) = 6*a(n-1) - a(n-2) - 28*a(n-3) - 4*a(n-4) + 16*a(n-5) - 4*a(n-6) for n>8.

Empirical g.f.: 3*x*(9 + 4*x - 141*x^2 + 148*x^3 + 82*x^4 - 38*x^5 - 24*x^6 + 8*x^7) / (1 - 3*x - 4*x^2 + 2*x^3)^2. - Colin Barker, Jan 18 2019

EXAMPLE

Some solutions for n=4:

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

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

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

CROSSREFS

Row 3 of A269052.

Sequence in context: A213285 A174617 A055339 * A248234 A083560 A125337

Adjacent sequences:  A269051 A269052 A269053 * A269055 A269056 A269057

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 18 2016

STATUS

approved

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Last modified June 22 21:29 EDT 2021. Contains 345393 sequences. (Running on oeis4.)