%I #8 Nov 28 2018 08:03:52
%S 9,22,52,125,297,710,1691,4036,9621,22951,54727,130529,311280,742388,
%T 1770476,4222417,10069902,24015598,57274225,136592357,325756272,
%U 776890181,1852790060,4418684023,10538033895,25131955837,59936717455
%N Number of (n+1) X (1+1) 0..1 arrays with every 2 X 2 subblock having a single 1 or two 1s on the same edge or main diagonally.
%H R. H. Hardin, <a href="/A251285/b251285.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 2*a(n-1) + 2*a(n-2) - 3*a(n-3) + a(n-4).
%F Empirical g.f.: x*(9 + 4*x - 10*x^2 + 4*x^3) / (1 - 2*x - 2*x^2 + 3*x^3 - x^4). - _Colin Barker_, Nov 28 2018
%e Some solutions for n=4:
%e ..0..0....0..1....0..0....0..1....0..1....1..0....1..1....1..0....1..0....0..0
%e ..1..1....0..0....0..1....0..0....0..0....0..0....0..0....1..0....1..0....0..1
%e ..0..0....0..1....0..0....0..1....1..0....1..0....1..0....1..0....0..1....0..1
%e ..0..1....0..0....1..0....0..1....0..0....0..0....0..1....0..0....0..0....0..0
%e ..0..0....0..1....1..0....0..1....1..0....1..1....0..0....1..1....1..0....1..0
%Y Column 1 of A251292.
%K nonn
%O 1,1
%A _R. H. Hardin_, Dec 01 2014
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