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 A046984 Number of ways to tile a 4 X 3n rectangle with right trominoes. 1
 1, 4, 18, 88, 468, 2672, 16072, 100064, 636368, 4097984, 26579488, 173093760, 1129796928, 7383588608, 48287978624, 315921649152, 2067346607360, 13530037877760, 88555066819072, 579620448450560, 3793872862974976 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 REFERENCES Suggested on p. 96 of 1994 edition of "Polyominoes" by Samuel W. Golomb. LINKS Index entries for linear recurrences with constant coefficients, signature (10, -22, -4). FORMULA G.f.: (1 - 6*x)/(1 - 10*x + 22*x^2 + 4*x^3). a(0)=1, a(1)=4, a(2)=18, a(n)=10*a(n-1)-22*a(n-2)-4*a(n-3). - Harvey P. Dale, Mar 31 2012 MATHEMATICA CoefficientList[Series[(1-6x)/(1-10x+22x^2+4x^3), {x, 0, 40}], x] (* or *) LinearRecurrence[{10, -22, -4}, {1, 4, 18}, 40] (* Harvey P. Dale, Mar 31 2012 *) PROG (PARI) a(n)=([0, 1, 0; 0, 0, 1; -4, -22, 10]^n*[1; 4; 18])[1, 1] \\ Charles R Greathouse IV, Feb 10 2017 CROSSREFS Sequence in context: A006629 A068764 A127394 * A129323 A000305 A200029 Adjacent sequences:  A046981 A046982 A046983 * A046985 A046986 A046987 KEYWORD nonn,easy,nice AUTHOR Cristopher Moore (moore(AT)santafe.edu) EXTENSIONS More terms from James A. Sellers STATUS approved

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Last modified October 23 05:44 EDT 2018. Contains 316519 sequences. (Running on oeis4.)