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 A189002 Number of domino tilings of the n X n grid with upper left corner removed iff n is odd. 2
 1, 1, 2, 4, 36, 192, 6728, 100352, 12988816, 557568000, 258584046368, 32565539635200, 53060477521960000, 19872369301840986112, 112202208776036178000000, 126231322912498539682594816, 2444888770250892795802079170816, 8326627661691818545121844900397056 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Alois P. Heinz, Table of n, a(n) for n = 0..50 FORMULA a(n) = A189006(n,n). EXAMPLE a(3) = 4 because there are 4 domino tilings of the 3 X 3 grid with upper left corner removed: . .___. . .___. . .___. . .___. ._|___| ._|___| ._| | | ._|___| | |___| | | | | | |_|_| |___| | |_|___| |_|_|_| |_|___| |___|_| MATHEMATICA A[1, 1] = 1; A[m_, n_] := A[m, n] = Module[{i, j, s, t, M}, Which[m == 0 || n == 0, 1, m < n, A[n, m], True, s = Mod[n*m, 2]; M[i_, j_] /; j < i := -M[j, i]; M[_, _] = 0; For[i = 1, i <= n, i++, For[j = 1, j <= m, j++, t = (i - 1)*m + j - s; If[i > 1 || j > 1 || s == 0, If[j < m, M[t, t + 1] = 1]; If[i < n, M[t, t + m] = 1 - 2*Mod[j, 2]]]]]; Sqrt[Det[Array[M, {n*m - s, n*m - s}]] ]]]; a[n_] := A[n, n]; a /@ Range[0, 17] (* Jean-François Alcover, Feb 27 2020, after Alois P. Heinz in A189006 *) CROSSREFS Main diagonal of A189006. Bisection gives: A004003 (even part), A007341 (odd part). Sequence in context: A277091 A199495 A182965 * A304558 A215251 A052716 Adjacent sequences:  A188999 A189000 A189001 * A189003 A189004 A189005 KEYWORD nonn AUTHOR Alois P. Heinz, Apr 15 2011 STATUS approved

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Last modified April 3 23:48 EDT 2020. Contains 333207 sequences. (Running on oeis4.)