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 A239265 Number of domicule tilings of a 3 X 2n grid. 2
 1, 5, 43, 451, 4945, 54685, 605707, 6710971, 74358721, 823915861, 9129240139, 101154812563, 1120826772817, 12419109262381, 137607593744107, 1524734943844939, 16894537473570817, 187196730554444581, 2074198005431257579, 22982759116542299875 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS A domicule is either a domino or it is formed by the union of two neighboring unit squares connected via their corners. In a tiling the connections of two domicules are allowed to cross each other. LINKS Alois P. Heinz, Table of n, a(n) for n = 0..950 Index entries for linear recurrences with constant coefficients, signature (13,-21,-3). FORMULA G.f.: -(x^2+8*x-1)/(3*x^3+21*x^2-13*x+1). EXAMPLE a(1) = 5: +---+ +---+ +---+ +---+ +---+ |o o| |o o| |o-o| |o-o| |o-o| | X | || || | | | | | | |o o| |o o| |o-o| |o o| |o o| | | | | | | || || | X | |o-o| |o-o| |o-o| |o o| |o o| +---+ +---+ +---+ +---+ +---+. MAPLE gf:= -(x^2+8*x-1)/(3*x^3+21*x^2-13*x+1): a:= n-> coeff(series(gf, x, n+1), x, n): seq(a(n), n=0..30); CROSSREFS Even bisection of column k=3 of A239264. Sequence in context: A156886 A112115 A350117 * A369023 A274666 A301976 Adjacent sequences: A239262 A239263 A239264 * A239266 A239267 A239268 KEYWORD nonn,easy AUTHOR Alois P. Heinz, Mar 13 2014 STATUS approved

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Last modified August 11 12:11 EDT 2024. Contains 375069 sequences. (Running on oeis4.)