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%I #9 Apr 19 2018 05:53:59
%S 246,1910,14825,115069,893145,6932452,53808589,417653681,3241761282,
%T 25162034228,195303697871,1515916163938,11766299569341,91328141257666,
%U 708874471232044,5502170623914248,42706971125717460,331484700748035803
%N Half the number of (n+2) X 3 binary arrays with each 3 X 3 subblock having a sum in 2..7.
%C Column 1 of A186796.
%H R. H. Hardin, <a href="/A186788/b186788.txt">Table of n, a(n) for n = 1..200</a>
%F Empirical: a(n) = 7*a(n-1) + 4*a(n-2) + 15*a(n-3) - 9*a(n-5).
%F Empirical g.f.: x*(246 + 188*x + 471*x^2 - 36*x^3 - 288*x^4) / (1 - 7*x - 4*x^2 - 15*x^3 + 9*x^5). - _Colin Barker_, Apr 19 2018
%e Some solutions for 4 X 3 with a(1,1)=0:
%e ..0..0..1....0..0..0....0..1..1....0..1..1....0..0..0....0..1..0....0..1..0
%e ..0..1..1....0..0..0....0..1..0....0..1..1....0..1..1....0..0..1....0..0..1
%e ..0..1..0....1..1..1....0..0..1....0..1..1....0..0..1....0..1..0....1..0..0
%e ..1..0..1....1..1..0....0..0..0....1..1..0....0..1..0....1..1..1....1..0..1
%Y Cf. A186796.
%K nonn
%O 1,1
%A _R. H. Hardin_, Feb 26 2011
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