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 A180752 Half the number of nX3 binary arrays with each element equal to at least two neighbors 1
 0, 1, 1, 2, 3, 7, 14, 31, 67, 148, 325, 717, 1580, 3485, 7685, 16950, 37383, 82451, 181850, 401083, 884615, 1951080, 4303241, 9491097, 20933272, 46169785, 101830665, 224594602, 495358987, 1092548639, 2409691878, 5314742743 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 COMMENTS Column 3 of A180760 LINKS R. H. Hardin, Table of n, a(n) for n=1..99 FORMULA Empirical: a(n) = 2*a(n-1) + a(n-2) - a(n-3) - a(n-5). Empirical: G.f.: -x^2*(-1+x+x^3+x^2) / ( (x-1)*(1+x)*(x^3+2*x-1) ). a(n)-a(n-2) = A052980(n-3). - R. J. Mathar, Mar 24 2018 CROSSREFS Sequence in context: A103421 A205484 A151530 * A000642 A348530 A229734 Adjacent sequences: A180749 A180750 A180751 * A180753 A180754 A180755 KEYWORD nonn AUTHOR R. H. Hardin Sep 20 2010 STATUS approved

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Last modified December 4 02:16 EST 2022. Contains 358544 sequences. (Running on oeis4.)