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 A189003 Number of domino tilings of the 5 X n grid with upper left corner removed iff n is odd. 3
 1, 1, 8, 15, 95, 192, 1183, 2415, 14824, 30305, 185921, 380160, 2332097, 4768673, 29253160, 59817135, 366944287, 750331584, 4602858719, 9411975375, 57737128904, 118061508289, 724240365697, 1480934568960, 9084693297025, 18576479568193, 113956161827912 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Alois P. Heinz, Table of n, a(n) for n = 0..550 Index entries for linear recurrences with constant coefficients, signature (0,15,0,-32,0,15,0,-1). FORMULA G.f.: (x-1)*(1+x)*(x^4+x^3-6*x^2+x+1) / (-x^8+15*x^6-32*x^4+15*x^2-1). MAPLE a:= n-> (<<0|1|0|0>, <0|0|1|0>, <0|0|0|1>, <-1|15|-32|15>>^iquo(n, 2, 'r').         `if`(r=0, <<8, 1, 1, 8>>, <<1, 0, 1, 15>>))[3, 1]: seq(a(n), n=0..30); MATHEMATICA a[n_] := Product[2(2+Cos[2 j Pi/(n+1)]+Cos[k Pi/3]), {k, 1, 2}, {j, 1, n/2} ] // Round; Table[a[n], {n, 0, 24}] (* Jean-François Alcover, Aug 19 2018, after A099390 *) CROSSREFS 5th row of array A189006. Bisections give: A003775 (even part), A006238 (odd part). Sequence in context: A275246 A177199 A177165 * A110294 A110459 A132374 Adjacent sequences:  A189000 A189001 A189002 * A189004 A189005 A189006 KEYWORD nonn,easy AUTHOR Alois P. Heinz, Apr 15 2011 STATUS approved

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Last modified April 7 01:11 EDT 2020. Contains 333291 sequences. (Running on oeis4.)