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

0,3

Comments

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

Links

Table of n, a(n) for n=0..24.

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).

Formula

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

Maple

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

Crossrefs

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

Sequence in context: A307073 A143787 A289973 * A025191 A282990 A099159

Adjacent sequences: A236580 A236581 A236582 * A236584 A236585 A236586

Keyword

easy,nonn

Author

R. J. Mathar, Jan 29 2014

Status

approved