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A319879
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a(n) = minimal number m of unit squares needed to make an figure formed from squares (joined edge to edge) which has n holes.
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0
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1, 8, 13, 18, 21, 26, 29, 34, 37, 40, 45, 48, 51, 56, 59, 62, 65, 70, 73, 76, 79, 84, 87, 90, 93, 96, 101, 104, 107, 110, 113, 118, 121, 124, 127, 130, 133, 138, 141, 144, 147, 150, 153, 158, 161, 164, 167, 170, 173, 176, 181
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,2
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COMMENTS
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The holes must not touch each other.
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REFERENCES
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Jean-Paul Delahaye, Des trous à entourer avec parcimonie, Pour las science, No. 501, Juillet 2019, pp. 82-87.
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LINKS
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EXAMPLE
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XOX
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XOXOX
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XOXOXOX
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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Entry 123 changed to 124 by the author, Jul 01 2019. - N. J. A. Sloane, Jul 01 2019
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STATUS
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approved
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