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A002013
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Filaments with n square cells.
(Formerly M0835 N0317)
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4
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1, 1, 1, 2, 3, 7, 13, 31, 65, 154, 347, 824, 1905, 4512, 10546, 24935, 58476, 138002, 323894, 763172, 1790585, 4213061, 9878541, 23214728
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,4
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COMMENTS
| Or, number of 2-sided strip polyominoes with n cells. - Ed Pegg, Jr., May 13 2009
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REFERENCES
| N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
R. C. Tilley, R. G. Stanton and D. D. Cowan, The cell growth problem for filaments, pp. 310-339 in Proceedings of the Louisiana Conference on Combinatorics, Graph Theory and Computer Science. Vol. 1, edited R. C. Mullin et al., 1970.
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LINKS
| Ed Pegg, Jr., Illustrations of polyforms
Eric Weisstein's World of Mathematics, Polyomino
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CROSSREFS
| Sequence in context: A102644 A014234 A124430 * A171416 A193530 A003120
Adjacent sequences: A002010 A002011 A002012 * A002014 A002015 A002016
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| a(23) from Joseph Myers (jsm(AT)polyomino.org.uk), Nov 22 2010
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