cp's OEIS Frontend

A219136 Unchanging value maps: number of n X 2 binary arrays indicating the locations of corresponding elements unequal to no horizontal, diagonal or antidiagonal neighbor in a random 0..2 n X 2 array.

%I A219136 #8 Mar 10 2018 08:37:04
%S A219136 2,6,18,51,142,405,1157,3289,9344,26580,75621,215076,611683,1739781,
%T A219136 4948421,14074414,40030688,113856507,323834334,921058929,2619701953,
%U A219136 7451032833,21192445976,60276171664,171439240421,487612482144
%N A219136 Unchanging value maps: number of n X 2 binary arrays indicating the locations of corresponding elements unequal to no horizontal, diagonal or antidiagonal neighbor in a random 0..2 n X 2 array.
%C A219136 Column 2 of A219142.
%H A219136 R. H. Hardin, <a href="/A219136/b219136.txt">Table of n, a(n) for n = 1..210</a>
%F A219136 Empirical: a(n) = 2*a(n-1) + a(n-2) + 3*a(n-3) + 4*a(n-4) - 2*a(n-5) - 4*a(n-6).
%F A219136 Empirical g.f.: x*(2 + 2*x + 4*x^2 + 3*x^3 - 4*x^4 - 4*x^5) / ((1 + 2*x^2)*(1 - 2*x - 3*x^2 + x^3 + 2*x^4)). - _Colin Barker_, Mar 10 2018
%e A219136 Some solutions for n=3:
%e A219136 ..1..0....0..0....0..0....0..0....1..1....0..0....0..0....0..0....1..1....0..0
%e A219136 ..0..0....1..0....0..0....0..0....0..1....0..1....1..0....0..1....1..0....0..0
%e A219136 ..0..1....1..1....1..0....0..0....0..0....0..0....0..0....1..1....0..0....1..1
%Y A219136 Cf. A219142.
%K A219136 nonn
%O A219136 1,1
%A A219136 _R. H. Hardin_, Nov 12 2012