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A251122 Number of (n+1) X (2+1) 0..1 arrays with no 2 X 2 subblock having the sum of its diagonal elements greater than the maximum of its antidiagonal elements.

%I A251122 #10 Nov 25 2018 11:44:59
%S A251122 21,40,69,117,193,315,510,823,1326,2136,3442,5550,8955,14458,23355,
%T A251122 37743,61015,98661,159564,258097,417516,675450,1092784,1768032,
%U A251122 2860593,4628380,7488705,12116793,19605181,31721631,51326442,83047675,134373690
%N A251122 Number of (n+1) X (2+1) 0..1 arrays with no 2 X 2 subblock having the sum of its diagonal elements greater than the maximum of its antidiagonal elements.
%H A251122 R. H. Hardin, <a href="/A251122/b251122.txt">Table of n, a(n) for n = 1..210</a>
%F A251122 Empirical: a(n) = 4*a(n-1) - 5*a(n-2) + a(n-3) + 2*a(n-4) - a(n-5).
%F A251122 Empirical g.f.: x*(21 - 44*x + 14*x^2 + 20*x^3 - 12*x^4) / ((1 - x)^3*(1 - x - x^2)). - _Colin Barker_, Nov 25 2018
%e A251122 Some solutions for n=4:
%e A251122 ..0..0..1....0..0..0....0..0..0....1..1..1....0..0..0....0..0..0....0..1..1
%e A251122 ..0..0..1....1..1..1....0..0..0....0..0..0....1..1..1....1..1..1....0..0..0
%e A251122 ..0..0..1....1..0..0....0..0..0....1..1..1....0..0..0....0..0..0....0..0..0
%e A251122 ..1..0..1....1..0..0....0..0..0....0..0..0....0..0..0....0..0..0....1..1..1
%e A251122 ..1..0..0....1..0..0....1..1..1....1..1..1....0..0..0....1..1..1....0..0..0
%Y A251122 Column 2 of A251128.
%K A251122 nonn
%O A251122 1,1
%A A251122 _R. H. Hardin_, Nov 30 2014