A226710 - OEIS

%I #7 Sep 06 2018 08:31:52

%S 3,9,25,67,181,491,1331,3607,9775,26491,71793,194565,527287,1428991,

%T 3872683,10495289,28443095,77083123,208901593,566140471,1534287165,

%U 4158044205,11268641233,30538943065,82763043409,224294643719

%N Number of n X 1 (-1,0,1) arrays of determinants of 2 X 2 subblocks of some (n+1) X 2 binary array.

%H R. H. Hardin, <a href="/A226710/b226710.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 2*a(n-1) + a(n-2) + 2*a(n-3) + a(n-4) + a(n-5).

%F Empirical g.f.: x*(3 + 3*x + 4*x^2 + 2*x^3 + x^4) / (1 - 2*x - x^2 - 2*x^3 - x^4 - x^5). - _Colin Barker_, Sep 06 2018

%e Some solutions for n=3:

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

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

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

%Y Column 1 of A226717.

%K nonn

%O 1,1

%A _R. H. Hardin_, Jun 15 2013