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A219870
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Number of tilings of a 7 X n rectangle using dominoes and straight (3 X 1) trominoes.
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2
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1, 3, 60, 1562, 29907, 707903, 15859323, 354859954, 8061851335, 181382499259, 4095897476480, 92476840837163, 2086314577400136, 47096964973772265, 1062921614745008697, 23989328157229264043, 541446343762904191567, 12220135872229640539724
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OFFSET
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0,2
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LINKS
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EXAMPLE
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a(1) = 3, because there are 3 tilings of a 7 X 1 rectangle using dominoes and straight (3 X 1) trominoes:
._. ._. ._.
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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