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 A279971 Number of n X 2 0..1 arrays with no element equal to a strict majority of its horizontal and antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards. 1

%I

%S 1,3,9,31,108,366,1205,3873,12207,37859,115842,350412,1049545,3116655,

%T 9185349,26890375,78253896,226510362,652483133,1871302893,5345409483,

%U 15213423371,43153001406,122024489304,344061371665,967537410459

%N Number of n X 2 0..1 arrays with no element equal to a strict majority of its horizontal and antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.

%H R. H. Hardin, <a href="/A279971/b279971.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 9*a(n-1) - 30*a(n-2) + 45*a(n-3) - 30*a(n-4) + 9*a(n-5) -a(n-6).

%F Empirical g.f.: x*(1 - 2*x)*(1 - 4*x + 4*x^2 + 3*x^3) / (1 - 3*x + x^2)^3. - _Colin Barker_, Feb 12 2019

%e Some solutions for n=4:

%e ..0..0. .0..1. .0..1. .0..1. .0..1. .0..1. .0..0. .0..0. .0..0. .0..0

%e ..1..1. .0..0. .1..0. .1..1. .0..1. .1..0. .1..0. .1..0. .1..1. .1..0

%e ..1..0. .0..1. .0..0. .1..0. .0..1. .1..0. .1..0. .1..1. .0..0. .1..1

%e ..0..1. .0..0. .0..1. .0..1. .1..1. .0..0. .1..1. .1..0. .0..1. .0..0

%Y Column 2 of A279977.

%K nonn

%O 1,2

%A _R. H. Hardin_, Dec 24 2016

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Last modified August 12 17:17 EDT 2020. Contains 336439 sequences. (Running on oeis4.)