

A236577


The number of tilings of a 6 X n floor with 1 X 3 trominoes.


5



1, 1, 1, 6, 13, 22, 64, 155, 321, 783, 1888, 4233, 9912, 23494, 54177, 126019, 295681, 687690, 1600185, 3738332, 8712992, 20293761, 47337405, 110368563, 257206012, 599684007, 1398149988, 3259051800, 7597720649, 17712981963
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OFFSET

0,4


COMMENTS

Tilings are counted irrespective of internal symmetry: Tilings that match each other after rotations and/or reflections are counted with their multiplicity.


LINKS

Index entries for linear recurrences with constant coefficients, signature (1,1,7,1,5,10,1,3,5,1,1,1).


FORMULA

G.f.: See the definition of g in the Maple code.


MAPLE

g := (1x^3)^2*(x^2+1x^3)/ (x^10+x^12+x^11+10*x^65*x^93*x^8+x^7+x^47*x^3+5*x^5x^2x+1) ;
taylor(%, x=0, 30) ;
gfun[seriestolist](%) ;


MATHEMATICA

CoefficientList[Series[(1  x^3)^2*(x^2 + 1  x^3)/(x^10 + x^12 + x^11 + 10*x^6  5*x^9  3*x^8 + x^7 + x^4  7*x^3 + 5*x^5  x^2  x + 1), {x, 0, 50}], x] (* G. C. Greubel, Apr 27 2017 *)


PROG

(PARI) x='x+O('x^50); Vec((1x^3)^2*(x^2+1x^3)/(x^10+x^12+x^11+10*x^6 5*x^93*x^8+x^7+x^47*x^3+5*x^5x^2x+1)) \\ G. C. Greubel, Apr 27 2017


CROSSREFS



KEYWORD

nonn,easy


AUTHOR



STATUS

approved



