A233266 Number of tilings of a 4 X n rectangle using tetrominoes of shapes L, T, Z.

1, 0, 2, 10, 24, 70, 276, 820, 2616, 8702, 27902, 89500, 291050, 939222, 3029950, 9798606, 31657182, 102237766, 330356240, 1067310022, 3447911968, 11139391996, 35988377472, 116265759012, 375619824338, 1213515477460, 3920484872552, 12665878390278

Offset

0,3

Links

Alois P. Heinz, Table of n, a(n) for n = 0..1000

Wikipedia, Tetromino

Index entries for linear recurrences with constant coefficients, signature (2, 4, 4, -6, -28, 15, 4, -13, 20, -4, 16, -10, 8, -2).

Formula

G.f.: (x^8 -4*x^7 +3*x^6 -2*x^5 -2*x^4 -2*x^3 +2*x^2 +2*x -1) / (-2*x^14 +8*x^13 -10*x^12 +16*x^11 -4*x^10 +20*x^9 -13*x^8 +4*x^7 +15*x^6 -28*x^5 -6*x^4 +4*x^3 +4*x^2 +2*x -1).

Example

a(3) = 10:
._____.  ._____.  ._____.  ._____.  ._____.
| |_. |  | ._| |  | .___|  |___. |  | .___|
|_. | |  | | ._|  |_| | |  | | |_|  |_| ._|
| |_|_|  |_|_| |  | ._| |  | |_. |  |___| |
|_____|  |_____|  |_|___|  |___|_|  |_____|
._____.  ._____.  ._____.  ._____.  ._____.
| ._| |  | |_. |  |_. ._|  |_. ._|  |___. |
| |_. |  | ._| |  | |_| |  | |_| |  |_. |_|
|_| |_|  |_| |_|  | |_. |  | ._| |  | |___|
|_____|  |_____|  |___|_|  |_|___|  |_____|.

Crossrefs

Cf. A084480, A174248, A226322, A230031, A232497, A233139, A233191, A242636.

Sequence in context: A295053 A130016 A120550 * A222848 A119062 A270822

Adjacent sequences: A233263 A233264 A233265 * A233267 A233268 A233269

Keyword

nonn,easy

Author

Alois P. Heinz, Dec 06 2013

Status

approved