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%I #7 Jul 25 2018 08:06:10
%S 2,4,9,21,49,115,269,628,1468,3433,8025,18758,43851,102512,239638,
%T 560193,1309554,3061318,7156366,16729268,39107635,91421020,213712795,
%U 499591476,1167883505,2730134349,6382172117,14919456700,34876870155,81530855583
%N Unchanging value maps: number of n X 2 binary arrays indicating the locations of corresponding elements unequal to no horizontal, antidiagonal or vertical neighbor in a random 0..1 n X 2 array.
%C Column 2 of A219156.
%H R. H. Hardin, <a href="/A219150/b219150.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 2*a(n-1) - a(n-2) + 4*a(n-3) + a(n-5).
%F Empirical g.f.: x*(2 + 3*x^2 - x^3) / (1 - 2*x + x^2 - 4*x^3 - x^5). - _Colin Barker_, Jul 25 2018
%e All solutions for n=3:
%e ..0..0....1..0....0..0....1..1....0..0....0..0....1..1....1..1....1..0
%e ..0..0....0..0....0..0....1..1....0..0....0..1....0..0....1..0....0..0
%e ..0..0....0..0....1..1....1..1....0..1....1..1....0..0....0..0....0..1
%Y Cf. A219156.
%K nonn
%O 1,1
%A _R. H. Hardin_, Nov 12 2012