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 A271802 Number of cuttings of an n X n checkerboard along grid lines into two pieces with holes disallowed. 1
 0, 6, 52, 614, 16000, 1114394, 220762028, 127074234622, 215163221802400, 1080509693050320314, 16181730102294154610684, 725449589191165593072311582, 97631783799192329642727718567824, 39528641527526180063041016094650084850 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Equivalently, the number of partitionings of an n X n checkerboard into two edgewise-connected simply-connected sets. (Cf. A068416). Each part is required to contain at least one cell and cuttings are considered different if they only differ by rotation or reflection. LINKS FORMULA a(n) = A068416(n) - A140517(n-2). MATHEMATICA A068416 = Cases[Import["https://oeis.org/A068416/b068416.txt", "Table"], {_, _}][[All, 2]]; A140517 = Cases[Import["https://oeis.org/A140517/b140517.txt", "Table"], {_, _}][[All, 2]]; a[n_] := If[n == 1, 0, A068416[[n]] - A140517[[n - 1]]]; Array[a, 14] (* Jean-François Alcover, Sep 15 2019 *) CROSSREFS Sequence in context: A144345 A294158 A209306 * A097820 A166889 A164894 Adjacent sequences:  A271799 A271800 A271801 * A271803 A271804 A271805 KEYWORD nonn AUTHOR Andrew Howroyd, Apr 14 2016 STATUS approved

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Last modified September 27 07:28 EDT 2021. Contains 347673 sequences. (Running on oeis4.)