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A102380
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Irregular triangle read by rows in which row n lists prime factors (with multiplicity) of the repunit (10^n - 1)/9 (A002275(n)).
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15
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1, 11, 3, 37, 11, 101, 41, 271, 3, 7, 11, 13, 37, 239, 4649, 11, 73, 101, 137, 3, 3, 37, 333667, 11, 41, 271, 9091, 21649, 513239, 3, 7, 11, 13, 37, 101, 9901, 53, 79, 265371653, 11, 239, 4649, 909091, 3, 31, 37, 41, 271, 2906161, 11, 17, 73, 101
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,2
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COMMENTS
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See A003020 for other links and references.
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LINKS
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EXAMPLE
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First rows:
1;
11;
3, 37;
11, 101;
41, 271;
3, 7, 11, 13, 37;
239, 4649;
...
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MAPLE
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[seq( ifactor((10^n-1)/9), n=1..20)];
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CROSSREFS
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KEYWORD
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nonn,tabf
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AUTHOR
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EXTENSIONS
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First 100 rows in b-file from T. D. Noe, Feb 27 2009
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STATUS
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approved
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