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A219970 Number of tilings of a 6 X n rectangle using straight (3 X 1) trominoes and 2 X 2 tiles. 2
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified August 14 13:43 EDT 2022. Contains 356117 sequences. (Running on oeis4.)