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%I #8 Dec 26 2018 08:58:50
%S 18,29,69,133,236,472,940,1781,3433,6725,13008,25088,48696,94445,
%T 182717,353893,685924,1328520,2572916,4984581,9656065,18703333,
%U 36229992,70182768,135948832,263342141,510120437,988149701,1914124956,3707828408
%N Number of (n+2) X (1+2) 0..1 arrays with each 3 X 3 subblock having clockwise perimeter pattern 00000000 or 00000001.
%H R. H. Hardin, <a href="/A259635/b259635.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = a(n-1) + 3*a(n-3) + a(n-4) for n>5.
%F Empirical g.f.: x*(18 + 11*x + 40*x^2 + 10*x^3 - 2*x^4) / (1 - x - 3*x^3 - x^4). - _Colin Barker_, Dec 26 2018
%e Some solutions for n=4:
%e ..0..1..0....0..0..0....0..1..0....0..0..0....0..0..0....0..0..1....0..0..0
%e ..0..1..0....0..0..0....0..1..0....0..0..0....0..1..0....0..0..0....0..0..1
%e ..0..0..0....0..1..0....0..0..0....0..0..0....0..0..0....0..0..0....0..0..0
%e ..0..0..0....0..0..0....0..0..0....1..0..0....0..0..0....0..0..0....0..0..0
%e ..0..1..0....0..0..0....0..1..0....0..0..0....0..0..0....0..0..0....0..0..0
%e ..0..1..0....0..0..1....1..0..0....0..0..0....1..0..0....0..1..0....0..0..0
%Y Column 1 of A259642.
%K nonn
%O 1,1
%A _R. H. Hardin_, Jul 02 2015
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