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%I A303631 #8 Oct 29 2023 00:27:18
%S A303631 0,1,0,1,0,3,2,9,12,33,56,129,244,523,1034,2153,4336,8921,18104,37065,
%T A303631 75456,154171,314266,641569,1308492,2670345,5447424,11115417,22677188,
%U A303631 46269875,94401330,192609073,392973504,801784337,1635862800,3337639217
%N A303631 Number of n X 3 0..1 arrays with every element unequal to 2 or 3 horizontally or vertically adjacent elements, with upper left element zero.
%C A303631 Column 3 of A303636.
%H A303631 R. H. Hardin, <a href="/A303631/b303631.txt">Table of n, a(n) for n = 1..210</a>
%F A303631 Empirical: a(n) = a(n-1) +2*a(n-2) +a(n-4) -a(n-5).
%e A303631 All solutions for n=4:
%e A303631 ..0..1..0
%e A303631 ..1..0..1
%e A303631 ..1..0..1
%e A303631 ..0..1..0
%Y A303631 Cf. A303636.
%K A303631 nonn
%O A303631 1,6
%A A303631 _R. H. Hardin_, Apr 27 2018

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