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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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10
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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; internal format)
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OFFSET
| 1,2
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COMMENTS
| See A003020 for other links and references.
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REFERENCES
| Samuel Yates, The Mystique of Repunits, Math. Mag. 51 (1978), 22-28.
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LINKS
| T. D. Noe, Rows n=1..100 of triangle, flattened (derived from Yousuke Koide)
Makoto Kamada, Factorizations of 11...11 (repunit).
Yousuke Koide, Factorizations of Repunit Numbers
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EXAMPLE
| 1; (11); (3) (37); (11) (101); (41) (271); (3) (7) (11) (13) (37); (239) (4649); ...
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MAPLE
| [seq( ifactor((10^n-1)/9), n=1..20)];
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CROSSREFS
| Cf. A002275, A067063, A003020, A204845, A204846, A204847, A204848.
Sequence in context: A088653 A107598 A087100 * A204845 A147555 A157883
Adjacent sequences: A102377 A102378 A102379 * A102381 A102382 A102383
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KEYWORD
| nonn,tabf
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Nov 28 2006
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