A268881 - OEIS

A268881

Number of n X 3 binary arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling two exactly once.

2, 14, 84, 462, 2418, 12252, 60666, 295230, 1417452, 6732102, 31690914, 148080468, 687592338, 3175567374, 14597507076, 66827528094, 304831251762, 1386004252620, 6283722000714, 28414577975934, 128187044049948, 577056144993366

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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 A339281 A361552

Adjacent sequences: A268878 A268879 A268880 * A268882 A268883 A268884

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 15 2016

STATUS

approved