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A281050 Number of n X 2 0..1 arrays with no element equal to more than one of its horizontal and antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.

%I A281050 #8 Feb 15 2019 04:40:39
%S A281050 0,1,6,29,122,468,1686,5807,19338,62731,199264,622152,1914780,5821645,
%T A281050 17515566,52221929,154461110,453654108,1324053522,3842768987,
%U A281050 11096398578,31895230903,91296545404,260329675536,739725018360,2095147333465
%N A281050 Number of n X 2 0..1 arrays with no element equal to more than one of its horizontal and antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.
%H A281050 R. H. Hardin, <a href="/A281050/b281050.txt">Table of n, a(n) for n = 1..210</a>
%F A281050 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 A281050 Empirical g.f.: x^2*(1 - 3*x + 5*x^2 - 4*x^3) / (1 - 3*x + x^2)^3. - _Colin Barker_, Feb 15 2019
%e A281050 Some solutions for n=4:
%e A281050 ..0..0. .0..0. .0..1. .0..0. .0..0. .0..1. .0..0. .0..0. .0..0. .0..0
%e A281050 ..0..0. .1..1. .1..1. .0..0. .0..1. .1..1. .1..1. .1..1. .0..0. .0..1
%e A281050 ..1..0. .1..1. .0..0. .1..0. .0..1. .1..0. .0..0. .1..1. .1..1. .1..1
%e A281050 ..0..1. .0..0. .0..1. .1..0. .1..1. .1..0. .0..0. .0..1. .0..1. .0..0
%Y A281050 Column 2 of A281056.
%K A281050 nonn
%O A281050 1,3
%A A281050 _R. H. Hardin_, Jan 13 2017