A219973 Number of tilings of a 9 X n rectangle using straight (3 X 1) trominoes and 2 X 2 tiles.

1, 1, 5, 35, 165, 1177, 9407, 55657, 372429, 2766100, 17671945, 118674685, 837152398, 5531816082, 37328192350, 257252634864, 1725117502706, 11666552132346, 79612474584518, 537157628862720, 3636277021289585, 24711657036469040, 167150255133278869

Offset

0,3

Links

Alois P. Heinz, Table of n, a(n) for n = 0..50

Example

a(2) = 5, because there are 5 tilings of a 9 X 2 rectangle using straight (3 X 1) trominoes and 2 X 2 tiles:
.___.   .___.   .___.   .___.   .___.
| | |   | | |   |   |   |   |   |   |
| | |   | | |   |___|   |___|   |___|
|_|_|   |_|_|   | | |   |   |   |   |
| | |   |   |   | | |   |___|   |___|
| | |   |___|   |_|_|   | | |   |   |
|_|_|   |   |   |   |   | | |   |___|
| | |   |___|   |___|   |_|_|   | | |
| | |   |   |   |   |   |   |   | | |
|_|_|   |___|   |___|   |___|   |_|_|

Crossrefs

Column k=9 of A219967.

Sequence in context: A184707 A124793 A048515 * A100739 A329762 A359520

Adjacent sequences: A219970 A219971 A219972 * A219974 A219975 A219976

Keyword

nonn

Author

Alois P. Heinz, Dec 02 2012

Status

approved