cp's OEIS Frontend

A186120 Number of (n+1) X 2 binary arrays with every 2 X 2 subblock diagonal sum less antidiagonal sum equal to some horizontal or vertical neighbor 2 X 2 subblock diagonal sum less antidiagonal sum.

%I A186120 #12 Apr 17 2018 12:13:02
%S A186120 0,14,18,50,74,182,298,678,1186,2566,4690,9830,18498,38006,72914,
%T A186120 147974,287554,579222,1135282,2276710,4488226,8978102,17768850,
%U A186120 35496326,70442882,140631254,279616498,558094758,1111168738,2217823222,4420075090
%N A186120 Number of (n+1) X 2 binary arrays with every 2 X 2 subblock diagonal sum less antidiagonal sum equal to some horizontal or vertical neighbor 2 X 2 subblock diagonal sum less antidiagonal sum.
%C A186120 Column 1 of A186128.
%H A186120 R. H. Hardin, <a href="/A186120/b186120.txt">Table of n, a(n) for n = 1..200</a>
%F A186120 Empirical: a(n) = 3*a(n-1) - 6*a(n-3) + 6*a(n-4) - 4*a(n-5) for n>6.
%F A186120 Empirical g.f.: 2*x^2*(7 - 12*x - 2*x^2 + 4*x^3 - 8*x^4) / ((1 - 2*x)*(1 - x - 2*x^2 + 2*x^3 - 2*x^4)). - _Colin Barker_, Apr 17 2018
%e A186120 Some solutions for 3 X 2:
%e A186120 ..0..1....1..1....1..0....0..0....1..1....0..0....1..0....1..0....0..1....0..1
%e A186120 ..0..0....0..0....1..1....1..1....0..0....0..0....0..0....1..0....0..1....1..1
%e A186120 ..1..0....1..1....0..1....0..0....0..0....1..1....0..1....1..0....0..1....1..0
%Y A186120 Cf. A186128.
%K A186120 nonn
%O A186120 1,2
%A A186120 _R. H. Hardin_, Feb 13 2011