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%I #8 Nov 28 2018 16:44:00
%S 28,116,474,1982,8218,34288,142600,594236,2473510,10302766,42897286,
%T 178649320,743905252,3097889852,12900178658,53720031766,223702349874,
%U 931554901848,3879218692624,16154045069844,67269408740158
%N Number of (n+1) X (2+1) 0..1 arrays with every 2 X 2 subblock having one or two 1s.
%H R. H. Hardin, <a href="/A251320/b251320.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 3*a(n-1) + 8*a(n-2) - 13*a(n-3) - a(n-4) + 2*a(n-5).
%F Empirical g.f.: 2*x*(14 + 16*x - 49*x^2 - 2*x^3 + 8*x^4) / ((1 + 2*x - x^2)*(1 - 5*x + 3*x^2 + 2*x^3)). - _Colin Barker_, Nov 28 2018
%e Some solutions for n=4:
%e ..1..1..1....1..0..1....0..0..1....1..0..1....0..0..1....1..0..0....0..1..0
%e ..0..0..0....0..0..1....1..0..0....1..0..1....1..0..1....1..0..1....0..1..0
%e ..0..1..1....0..1..0....0..1..0....1..0..0....0..1..0....0..0..1....1..0..1
%e ..1..0..0....0..0..1....0..0..1....0..0..1....0..1..0....1..0..1....1..0..1
%e ..1..0..1....1..0..1....1..0..1....1..0..0....1..0..0....1..0..0....0..0..0
%Y Column 2 of A251326.
%K nonn
%O 1,1
%A _R. H. Hardin_, Dec 01 2014
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