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A233266 Number of tilings of a 4 X n rectangle using tetrominoes of shapes L, T, Z. 7
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

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

Wikipedia, Tetromino

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

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Last modified August 20 06:04 EDT 2019. Contains 326139 sequences. (Running on oeis4.)