A236583 The number of tilings of an 8 X (3n) floor with 2 X 3 hexominoes.

1, 1, 4, 11, 33, 96, 281, 821, 2400, 7015, 20505, 59936, 175193, 512089, 1496836, 4375251, 12788857, 37381824, 109267057, 319387565, 933569728, 2728823951, 7976351345, 23314871872, 68149361393

Offset: 0

Author

R. J. Mathar, Jan 29 2014

Keywords

• easy
• nonn

Comments

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

Links

• R. J. Mathar, Paving rectangular regions..., arXiv:1311.6135, Table 51.
• R. J. Mathar, Tilings of Rectangular Regions by Rectangular Tiles: Counts Derived from Transfer Matrices, arXiv:1406.7788 [math.CO], eq. (34).
• Index entries for linear recurrences with constant coefficients, signature (3,0,-1,1).

Crossrefs

Cf. A000079 (5 X n floor), A182097 (6 X n floor), A000244 (7 X n floor), A236584 (9 x 2n floor)

Programs

Maple

g := (-1+x)^2/(x^3-x^4+1-3*x) ;
taylor(%,x=0,30) ;
gfun[seriestolist](%) ;

Formula

G.f.: (-1+x)^2/(x^3-x^4+1-3*x).