A219970 Number of tilings of a 6 X n rectangle using straight (3 X 1) trominoes and 2 X 2 tiles.

1, 1, 2, 8, 21, 65, 267, 804, 2530, 9407, 29876, 96530, 337607, 1100968, 3612017, 12284181, 40538721, 133971666, 450045654, 1492504271, 4949649998, 16537407509, 54951656907, 182545459254, 608458757050, 2023395434235, 6727009100372, 22399013790607

Offset

0,3

Links

Alois P. Heinz, Table of n, a(n) for n = 0..600

Example

a(2) = 2, because there are 2 tilings of a 6 X 2 rectangle using straight (3 X 1) trominoes and 2 X 2 tiles:
._._.   .___.
| | |   |   |
| | |   |___|
|_|_|   |   |
| | |   |___|
| | |   |   |
|_|_|   |___|

Crossrefs

Column k=6 of A219967.

Sequence in context: A123285 A143212 A316270 * A107361 A185309 A318040

Adjacent sequences: A219967 A219968 A219969 * A219971 A219972 A219973

Keyword

nonn

Author

Alois P. Heinz, Dec 02 2012

Status

approved