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Number of edge covers in the grid graph P_3 X P_n.
2

%I #10 Jun 11 2017 18:51:09

%S 1,43,969,23663,571099,13807469,333735575,8066926825,194989463233,

%T 4713185791699,113924706164937,2753729539353359,66561737202707371,

%U 1608896152717277333,38889412128248718215,940014912175876488361,22721558047666401897553,549213840574693856578267

%N Number of edge covers in the grid graph P_3 X P_n.

%H Andrew Howroyd, <a href="/A288031/b288031.txt">Table of n, a(n) for n = 1..200</a>

%F Empirical: a(n) = 20*a(n-1)+100*a(n-2)+24*a(n-3) -95*a(n-4)+10*a(n-5)+8*a(n-6) for n>6.

%F Empirical g.f.: x*(1 + 23*x + 9*x^2 - 41*x^3 + 2*x^4 + 8*x^5) / (1 - 20*x - 100*x^2 - 24*x^3 + 95*x^4 - 10*x^5 - 8*x^6). - _Colin Barker_, Jun 11 2017

%Y Row 3 of A286912.

%Y Cf. A286911, A286913.

%K nonn

%O 1,2

%A _Andrew Howroyd_, Jun 04 2017