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A268881 Number of n X 3 binary arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling two exactly once. 1
2, 14, 84, 462, 2418, 12252, 60666, 295230, 1417452, 6732102, 31690914, 148080468, 687592338, 3175567374, 14597507076, 66827528094, 304831251762, 1386004252620, 6283722000714, 28414577975934, 128187044049948, 577056144993366 (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) = 10*a(n-1) - 31*a(n-2) + 30*a(n-3) - 9*a(n-4).

Empirical g.f.: 2*x*(1 - 2*x)*(1 - x + x^2) / (1 - 5*x + 3*x^2)^2. - Colin Barker, Jan 15 2019

EXAMPLE

Some solutions for n=4:

..0..1..0. .0..0..0. .1..0..0. .0..1..0. .0..1..1. .1..0..1. .1..0..0

..0..1..0. .0..1..0. .1..1..0. .0..1..0. .0..0..0. .0..0..0. .1..0..0

..1..0..0. .0..0..1. .0..0..1. .1..0..0. .1..0..0. .1..1..0. .1..1..0

..0..0..1. .0..1..0. .1..0..0. .1..0..1. .1..0..0. .0..0..0. .0..1..0

CROSSREFS

Column 3 of A268886.

Sequence in context: A077444 A335693 A138126 * A053141 A036692 A075140

Adjacent sequences:  A268878 A268879 A268880 * A268882 A268883 A268884

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 15 2016

STATUS

approved

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Last modified September 23 21:27 EDT 2020. Contains 337315 sequences. (Running on oeis4.)