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 A227959 Number of tilings using monominoes and L-triominoes in 2 X n chessboard, such that three monominoes cannot occur together in shape of L-triomino. 1
 1, 1, 4, 6, 20, 38, 104, 220, 556, 1244, 3024, 6944, 16576, 38536, 91216, 213280, 502864, 1178928, 2774592, 6512864, 15315072, 35969952, 84550912, 198634048, 466825152, 1096838208, 2577550336, 6056474880, 14232064256, 33441977216, 78583660288, 184655188480 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Gopinath A. R., Table of n, a(n) for n = 0..200 Calvin Lin, Tiling, Discrete Mathematics Problem on Linear Recurrence Relations, Brilliant. Index entries for linear recurrences with constant coefficients, signature (0,4,2,2,4). FORMULA a(n) = 4*a(n-2) + 2*a(n-3) + 2*a(n-4) + 4*a(n-5), with a(0)=1, a(1)=1, a(2)=4, a(3)=6, and a(4)=20. G.f.: (1+x)/(1-4*x^2-2*x^3-2*x^4-4*x^5). Asymptotic formula: a(n) ~ 0.581189405182598 * 2.3498153157195^n. MATHEMATICA LinearRecurrence[{0, 4, 2, 2, 4}, {1, 1, 4, 6, 20}, 33] (* or *) CoefficientList[Series[(1 + x)/(1 - 4 x^2 - 2 x^3 - 2 x^4 - 4 x^5), {x, 0, 33}], x] (* Vincenzo Librandi, Apr 30 2018 *) PROG (Sage) fx = (1+x)/(1-4*x^2-2*x^3-2*x^4-4*x^5) fxt = taylor(fx, x, 0, 50) for i in range(51): ....print i, fxt.coefficient(x, i) (PARI) Vec( (1+x)/(1-4*x^2-2*x^3-2*x^4-4*x^5) +O(x^66) ) \\ Joerg Arndt, Aug 07 2013 (MAGMA) I:=[1, 1, 4, 6, 20]; [n le 5 select I[n] else 4*Self(n-2)+2*Self(n-3)+ 2*Self(n-4)+4*Self(n-5): n in [1..35]]; // Vincenzo Librandi, Apr 30 2018 CROSSREFS Cf. A127864. Sequence in context: A273995 A026788 A079435 * A088015 A027377 A048789 Adjacent sequences:  A227956 A227957 A227958 * A227960 A227961 A227962 KEYWORD nonn,easy AUTHOR Gopinath A. R., Aug 01 2013 STATUS approved

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Last modified January 24 13:24 EST 2020. Contains 331193 sequences. (Running on oeis4.)