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A288031
Number of edge covers in the grid graph P_3 X P_n.
2
1, 43, 969, 23663, 571099, 13807469, 333735575, 8066926825, 194989463233, 4713185791699, 113924706164937, 2753729539353359, 66561737202707371, 1608896152717277333, 38889412128248718215, 940014912175876488361, 22721558047666401897553, 549213840574693856578267
OFFSET
1,2
LINKS
FORMULA
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.
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
CROSSREFS
Row 3 of A286912.
Sequence in context: A162412 A010995 A253915 * A265658 A214100 A229432
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Jun 04 2017
STATUS
approved