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A269083 Number of n X 2 binary arrays with some element plus some horizontally, vertically or antidiagonally adjacent neighbor totalling two not more than once. 1
4, 11, 30, 76, 191, 467, 1127, 2686, 6339, 14840, 34504, 79759, 183445, 420077, 958248, 2178427, 4937234, 11159252, 25160111, 56599879, 127066227, 284728994, 636922003, 1422499564, 3172350160, 7065116255, 15714769641, 34912773337 (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) = 2*a(n-1) + 3*a(n-2) - 2*a(n-3) - 6*a(n-4) - 4*a(n-5) - a(n-6).

Empirical g.f.: x*(4 + 3*x - 4*x^2 - 9*x^3 - 5*x^4 - x^5) / (1 - x - 2*x^2 - x^3)^2. - Colin Barker, Jan 19 2019

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Column 2 of A269089.

Sequence in context: A099065 A296262 A102281 * A026583 A291238 A110034

Adjacent sequences:  A269080 A269081 A269082 * A269084 A269085 A269086

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 19 2016

STATUS

approved

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Last modified September 19 23:31 EDT 2019. Contains 327207 sequences. (Running on oeis4.)