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%I #8 Feb 15 2018 15:24:05
%S 21,26,65,250,541,1225,2583,5488,11899,25570,54750,117697,252985,
%T 543115,1166472,2505919,5382274,11560042,24830445,53333641,114554095,
%U 246050920,528494067,1135150426,2438187262,5236983073,11248510665,24160660963
%N Number of n X 7 0..1 arrays with every element unequal to 0, 1 or 4 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.
%C Column 7 of A299595.
%H R. H. Hardin, <a href="/A299594/b299594.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = a(n-1) +a(n-2) +3*a(n-3) +a(n-4) -a(n-5) -a(n-6) for n>9.
%F Empirical g.f.: x*(21 + 5*x + 18*x^2 + 96*x^3 + 127*x^4 + 234*x^5 + 49*x^6 - 102*x^7 - 73*x^8) / ((1 + x^2 - x^3)*(1 - x - 2*x^2 - x^3)). - _Colin Barker_, Feb 15 2018
%e Some solutions for n=5:
%e ..0..0..0..1..0..0..0. .0..0..0..0..0..0..0. .0..0..0..0..1..0..0
%e ..0..0..0..0..0..0..0. .0..0..0..0..0..0..0. .0..0..0..0..0..0..0
%e ..0..0..0..0..0..0..0. .0..0..0..0..0..0..0. .1..0..0..0..0..0..1
%e ..1..0..0..0..0..0..0. .0..0..0..0..0..0..0. .0..0..0..0..0..0..0
%e ..0..0..0..0..0..1..0. .0..0..0..0..1..0..0. .0..0..0..0..0..0..0
%Y Cf. A299595.
%K nonn
%O 1,1
%A _R. H. Hardin_, Feb 13 2018
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