A232684 Number of tilings of a 6 X 2n rectangle with 3n tetrominoes of any shape.

1, 9, 2003, 178939, 22483347, 2569437089, 304446920314, 35704534261665, 4203065267122878, 494232382069456694, 58138539945306221167, 6838279451118114249916, 804352962762109905924360, 94610929453211737452277488, 11128526714790919845521179844

Offset

0,2

Links

Alois P. Heinz, Table of n, a(n) for n = 0..300

S. Butler, J. Ekstrand, S. Osborne, TETRIS Tiling, AMS Spring Central Sectional, Iowa State University, April 27-28 2013

Wikipedia, Tetromino

Example

a(1) = 9:
.___. .___. .___. .___. .___. .___. .___. .___. .___.
|   | | | | |   | |_. | |   | | ._| |   | | ._| |_. |
|___| | | | |___| | | | |___| | | | |___| | | | | | |
|   | | | | | | | | |_| |_. | |_| | | ._| |_| | | |_|
|___| |_|_| | | | |___| | | | |___| | | | | | | | | |
|   | |   | | | | |   | | |_| |   | |_| | | |_| |_| |
|___| |___| |_|_| |___| |___| |___| |___| |___| |___|.

Crossrefs

Cf. A174248, A232698, A232722.

Even bisection of column k=6 of A230031.

Sequence in context: A201845 A218692 A024125 * A039917 A162140 A006945

Adjacent sequences: A232681 A232682 A232683 * A232685 A232686 A232687

Keyword

nonn

Author

Alois P. Heinz, Nov 27 2013

Status

approved