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A185899 1/8 the number of n X 2 0..7 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors.

%I A185899 #12 Apr 17 2018 06:16:48
%S A185899 1,15,196,2765,38731,545328,7675381,108065699,1521488668,21421955457,
%T A185899 301612441375,4246586949080,59790307544569,841824567122343,
%U A185899 11852566615920436,166879587240301061,2349600516714827299
%N A185899 1/8 the number of n X 2 0..7 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors.
%C A185899 Column 2 of A185903.
%H A185899 R. H. Hardin, <a href="/A185899/b185899.txt">Table of n, a(n) for n = 1..200</a>
%F A185899 Empirical: a(n) = 13*a(n-1) + 27*a(n-2) - 147*a(n-3) - 245*a(n-4) - 343*a(n-5).
%F A185899 Empirical g.f.: x*(1 + 2*x - 26*x^2 - 41*x^3 - 56*x^4) / (1 - 13*x - 27*x^2 + 147*x^3 + 245*x^4 + 343*x^5). - _Colin Barker_, Apr 17 2018
%e A185899 Some solutions for 3 X 2 with a(1,1)=0:
%e A185899 ..0..1....0..0....0..6....0..0....0..0....0..0....0..0....0..0....0..0....0..7
%e A185899 ..0..1....7..0....0..6....0..6....4..0....2..2....5..2....1..1....4..4....0..7
%e A185899 ..1..1....7..7....5..5....6..6....4..0....3..3....5..2....3..3....1..1....7..7
%Y A185899 Cf. A185903.
%K A185899 nonn
%O A185899 1,2
%A A185899 _R. H. Hardin_, Feb 06 2011