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A056786
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Number of inequivalent connected planar figures that can be formed from n non-overlapping 1 X 2 rectangles (or dominoes).
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16
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1, 1, 4, 26, 255, 2874, 35520, 454491, 5954914, 79238402, 1067193518
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OFFSET
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0,3
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COMMENTS
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"Connected" means "connected by edges", rotations and reflections are not considered different, but the internal arrangement of the dominoes does matter.
I have verified the first three entries by hand. The terms 255 and 2874 were taken from the Vicher web page. - N. J. A. Sloane.
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LINKS
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CROSSREFS
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KEYWORD
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nonn,nice,more
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AUTHOR
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EXTENSIONS
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a(8) from Anton Betten, Jan 18 2013, added by N. J. A. Sloane, Jan 18 2013. Anton Betten also verified that a(0)-a(7) are correct.
a(9) from Anton Betten, Jan 25 2013, added by N. J. A. Sloane, Jan 26 2013. Anton Betten comments that he used 8 processors, each for about 1 and a half day (roughly 300 hours CPU time).
a(10) from Aaron N. Siegel, May 18 2022. [It took just 30 minutes to verify a(9) and 7.2 hours to compute a(10), on a single CPU core!]
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STATUS
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approved
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