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A203373 Number of (n+1) X 4 0..1 arrays with every 2 X 2 subblock having equal diagonal elements or equal antidiagonal elements.

%I A203373 #9 Jun 04 2018 09:22:28
%S A203373 108,748,5208,36300,253068,1764360,12301020,85762188,597930552,
%T A203373 4168748268,29064349260,202635502632,1412766774396,9849754525644,
%U A203373 68672102130648,478779201937548,3338029812632076,23272612897409352
%N A203373 Number of (n+1) X 4 0..1 arrays with every 2 X 2 subblock having equal diagonal elements or equal antidiagonal elements.
%C A203373 Column 3 of A203378.
%H A203373 R. H. Hardin, <a href="/A203373/b203373.txt">Table of n, a(n) for n = 1..210</a>
%F A203373 Empirical: a(n) = 9*a(n-1) -15*a(n-2) +6*a(n-3).
%F A203373 Empirical g.f.: 4*x*(27 - 56*x + 24*x^2) / (1 - 9*x + 15*x^2 - 6*x^3). - _Colin Barker_, Jun 04 2018
%e A203373 Some solutions for n=4:
%e A203373 ..1..1..1..0....0..1..1..0....0..0..1..0....1..1..0..0....0..1..1..1
%e A203373 ..0..1..1..1....1..1..0..1....0..0..0..1....0..1..1..0....0..0..1..1
%e A203373 ..1..1..0..1....0..1..1..0....1..0..0..0....1..0..1..1....0..1..1..0
%e A203373 ..1..0..1..1....1..1..1..1....0..1..0..1....0..0..0..1....1..0..1..1
%e A203373 ..0..0..0..1....0..1..0..1....0..0..1..0....0..1..0..0....1..1..0..1
%Y A203373 Cf. A203378.
%K A203373 nonn
%O A203373 1,1
%A A203373 _R. H. Hardin_, Dec 31 2011