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%I #8 Oct 29 2018 05:03:12
%S 4,25,129,637,3147,15590,77269,382933,1897681,9404215,46603960,
%T 230952833,1144520961,5671842895,28107656217,139291647132,
%U 690280357055,3420786394205,16952212872439,84009197931223,416320004365162
%N Number of n X 3 0..1 arrays with no element equal to exactly three horizontal or vertical neighbors, with new values 0..1 introduced in row major order.
%H R. H. Hardin, <a href="/A240631/b240631.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 4*a(n-1) + 4*a(n-2) + 2*a(n-3) + 7*a(n-4) + 6*a(n-5) - a(n-6) - a(n-7) - a(n-8).
%F Empirical g.f.: x*(4 + 9*x + 13*x^2 + 13*x^3 + 5*x^4 - 3*x^5 - 2*x^6 - x^7) / (1 - 4*x - 4*x^2 - 2*x^3 - 7*x^4 - 6*x^5 + x^6 + x^7 + x^8). - _Colin Barker_, Oct 29 2018
%e Some solutions for n=4:
%e ..0..1..0....0..1..1....0..1..1....0..1..0....0..0..1....0..0..0....0..1..1
%e ..1..1..0....1..0..0....0..1..0....1..1..1....0..0..1....0..1..0....1..0..0
%e ..1..0..1....0..1..1....0..1..0....0..1..1....1..1..0....1..1..1....0..0..1
%e ..0..0..1....1..0..0....0..1..0....0..0..0....1..0..0....0..1..1....1..1..0
%Y Column 3 of A240636.
%K nonn
%O 1,1
%A _R. H. Hardin_, Apr 09 2014
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