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A219971 Number of tilings of a 7 X n rectangle using straight (3 X 1) trominoes and 2 X 2 tiles. 2
1, 0, 3, 13, 31, 170, 804, 2744, 12343, 55657, 214485, 923990, 4008013, 16241904, 68963484, 293830787, 1216393406, 5135225641, 21711233759, 90692128053, 381960417890, 1609647053073, 6749229887672, 28396742081001, 119506154362773, 501879008939056 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
LINKS
EXAMPLE
a(2) = 3, because there are 3 tilings of a 7 X 2 rectangle using straight (3 X 1) trominoes and 2 X 2 tiles:
._._. .___. .___.
| | | | | | |
| | | |___| |___|
|_|_| | | | | |
| | | | | |___|
|___| |_|_| | | |
| | | | | | |
|___| |___| |_|_|
CROSSREFS
Column k=7 of A219967.
Sequence in context: A339945 A154834 A159047 * A073337 A128067 A052493
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Dec 02 2012
STATUS
approved

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Last modified April 17 04:22 EDT 2024. Contains 371756 sequences. (Running on oeis4.)