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A280175 Number of nX3 0..1 arrays with no element unequal to a strict majority of its horizontal, vertical and antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.

%I A280175 #4 Dec 28 2016 06:59:34
%S A280175 0,12,60,279,1082,3931,13720,46467,153650,499289,1598693,5059881,
%T A280175 15855622,49273183,152010000,466006394,1420614227,4309242893,
%U A280175 13013193556,39139655092,117289714264,350310455965,1043078536630,3097120192877
%N A280175 Number of nX3 0..1 arrays with no element unequal to a strict majority of its horizontal, vertical and antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.
%C A280175 Column 3 of A280180.
%H A280175 R. H. Hardin, <a href="/A280175/b280175.txt">Table of n, a(n) for n = 1..210</a>
%F A280175 Empirical: a(n) = 9*a(n-1) -24*a(n-2) -9*a(n-3) +147*a(n-4) -213*a(n-5) -80*a(n-6) +567*a(n-7) -624*a(n-8) -30*a(n-9) +711*a(n-10) -687*a(n-11) +215*a(n-12) +84*a(n-13) +3*a(n-14) -86*a(n-15) +27*a(n-16) +6*a(n-17) -17*a(n-18) -18*a(n-19) -6*a(n-20) -a(n-21) for n>28
%e A280175 Some solutions for n=4
%e A280175 ..0..0..0. .0..1..1. .0..1..1. .0..0..0. .0..1..1. .0..1..1. .0..1..0
%e A280175 ..0..1..0. .1..1..0. .0..1..1. .1..1..0. .1..1..1. .0..1..0. .0..0..0
%e A280175 ..1..0..0. .1..1..1. .0..1..0. .1..1..1. .1..0..1. .1..0..0. .0..0..0
%e A280175 ..1..1..1. .1..1..1. .1..1..0. .0..1..1. .1..1..1. .0..0..0. .1..0..0
%Y A280175 Cf. A280180.
%K A280175 nonn
%O A280175 1,2
%A A280175 _R. H. Hardin_, Dec 28 2016