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A054418
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Number of connected 3 X n binary matrices with rightmost column [1,1,1]', divided by 4.
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3
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1, 8, 53, 352, 2345, 15624, 104093, 693504, 4620369, 30782536, 205084165, 1366343392, 9103063929, 60647838152, 404057392237, 2691973550848, 17934881869985, 119488539398536, 796074997934037, 5303733776692576
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| A connected (0,1) matrix is one where you can get from any black square, i.e. a 1, to any other by chess king moves.
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REFERENCES
| R. Levy and J. Shapiro, Uniqueness in paint-by-numbers puzzles, preprint, 2000.
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FORMULA
| a(n)=7a(n-1)-3a(n-2)+5a(n-3).
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CROSSREFS
| Cf. A054417-A054421.
Sequence in context: A198846 A110099 A091870 * A070928 A180095 A189393
Adjacent sequences: A054415 A054416 A054417 * A054419 A054420 A054421
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), May 22 2000
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EXTENSIONS
| More terms from James A. Sellers (sellersj(AT)math.psu.edu), May 23 2000
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