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%I #14 Oct 27 2017 10:17:06
%S 6,40,213,1049,5034,23984,114069,542295,2577870,12253948,58249011,
%T 276885683,1316170990,6256394122,29739651711,141366874247,
%U 671984773580,3194266961582,15183887824311,72176324719925,343088799809408,1630866146364842,7752291502484181
%N Number of cycles in the grid graph P_4 X P_{n+1}.
%H Andrew Howroyd, <a href="/A288637/b288637.txt">Table of n, a(n) for n = 1..200</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/GraphCycle.html">Graph Cycle</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/GridGraph.html">Grid Graph</a>
%F Empirical: a(n) = 9*a(n-1)-27*a(n-2)+38*a(n-3)-29*a(n-4)+11*a(n-5)+a(n-6)-2*a(n-7) for n>7.
%F Empirical g.f.: x*(6 - 14*x + 15*x^2 - 16*x^3 - 2*x^4 + x^5) / ((1 - x)^2*(1 - 7*x + 12*x^2 - 7*x^3 + 3*x^4 + 2*x^5)). - _Colin Barker_, Jun 12 2017
%Y Row 3 of A231829.
%K nonn
%O 1,1
%A _Andrew Howroyd_, Jun 12 2017
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