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%I #4 Nov 23 2017 09:23:45
%S 4,29,147,774,4080,21489,113466,598374,3155426,16642084,87770692,
%T 462903372,2441353234,12875695490,67906455891,358138834199,
%U 1888825058236,9961667898631,52537860596653,277084804179135,1461345928848848
%N Number of nX3 0..1 arrays with each 1 horizontally or vertically adjacent to 1, 2 or 4 1s.
%C Column 3 of A295531.
%H R. H. Hardin, <a href="/A295526/b295526.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 4*a(n-1) +3*a(n-2) +15*a(n-3) +17*a(n-4) +40*a(n-5) -6*a(n-6) -12*a(n-7) +45*a(n-8) -21*a(n-9) -66*a(n-10) +7*a(n-11) +6*a(n-12) -6*a(n-13) +6*a(n-14) +a(n-15) -3*a(n-16) +a(n-18)
%e Some solutions for n=5
%e ..1..1..0. .1..1..0. .0..1..0. .1..1..1. .0..0..0. .0..1..0. .1..1..0
%e ..0..1..0. .0..0..0. .0..1..1. .1..0..1. .0..1..1. .1..1..1. .0..1..1
%e ..0..0..0. .1..1..0. .0..0..1. .1..1..0. .1..1..1. .1..1..1. .1..0..0
%e ..0..0..0. .0..0..0. .1..0..1. .0..0..0. .1..1..0. .0..1..0. .1..1..1
%e ..0..1..1. .0..1..1. .1..1..0. .1..1..0. .0..0..0. .0..0..0. .0..0..1
%Y Cf. A295531.
%K nonn
%O 1,1
%A _R. H. Hardin_, Nov 23 2017
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