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%I #9 Mar 02 2018 06:27:22
%S 0,1,1,2,3,6,11,23,47,103,226,518,1200,2867,6946,17234,43393,111418,
%T 290233,768819,2064637,5626757,15531220,43432402,122878654,351665399,
%U 1016952840,2970387672,8755225931,26027153206,77972236615,235260594303
%N Number of n X 1 0..7 arrays with values 0..7 introduced in row major order and each element equal to at least one horizontal or vertical neighbor.
%C Column 1 of A198661.
%H R. H. Hardin, <a href="/A198655/b198655.txt">Table of n, a(n) for n = 1..200</a>
%F Empirical: a(n) = 7*a(n-1) + a(n-2) - 97*a(n-3) + 105*a(n-4) + 531*a(n-5) - 757*a(n-6) - 1511*a(n-7) + 2143*a(n-8) + 2457*a(n-9) - 2689*a(n-10) - 2227*a(n-11) + 1198*a(n-12) + 840*a(n-13) for n>14.
%F Empirical g.f.: x^2*(1 - 6*x - 6*x^2 + 85*x^3 - 25*x^4 - 476*x^5 + 247*x^6 + 1348*x^7 - 523*x^8 - 1959*x^9 + 157*x^10 + 1157*x^11 + 309*x^12) / ((1 - x)*(1 + x)*(1 - 2*x)*(1 - x - x^2)*(1 - x - 3*x^2)*(1 - x - 4*x^2)*(1 - x - 5*x^2)*(1 - x - 7*x^2)). - _Colin Barker_, Mar 02 2018
%e All solutions for n=5:
%e ..0....0....0
%e ..0....0....0
%e ..0....1....0
%e ..0....1....1
%e ..0....1....1
%Y Cf. A198661.
%K nonn
%O 1,4
%A _R. H. Hardin_, Oct 28 2011
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