A203373 - OEIS

%I #9 Jun 04 2018 09:22:28

%S 108,748,5208,36300,253068,1764360,12301020,85762188,597930552,

%T 4168748268,29064349260,202635502632,1412766774396,9849754525644,

%U 68672102130648,478779201937548,3338029812632076,23272612897409352

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

%C Column 3 of A203378.

%H R. H. Hardin, <a href="/A203373/b203373.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 9*a(n-1) -15*a(n-2) +6*a(n-3).

%F 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 Some solutions for n=4:

%e ..1..1..1..0....0..1..1..0....0..0..1..0....1..1..0..0....0..1..1..1

%e ..0..1..1..1....1..1..0..1....0..0..0..1....0..1..1..0....0..0..1..1

%e ..1..1..0..1....0..1..1..0....1..0..0..0....1..0..1..1....0..1..1..0

%e ..1..0..1..1....1..1..1..1....0..1..0..1....0..0..0..1....1..0..1..1

%e ..0..0..0..1....0..1..0..1....0..0..1..0....0..1..0..0....1..1..0..1

%Y Cf. A203378.

%K nonn

%O 1,1

%A _R. H. Hardin_, Dec 31 2011