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A046412
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Repunits of length a(n) without having distinct prime factors.
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1
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9, 18, 22, 27, 36, 42, 44, 45, 54, 63, 66, 72, 78, 81, 84, 88, 90, 99, 108, 110, 111, 117, 126, 132, 135, 144, 153, 154, 156, 162, 168, 171, 176, 180, 189, 198, 205, 207, 210, 216, 220, 222, 225, 234, 242, 243, 252, 261, 264, 270, 272, 279, 286, 288, 294, 297
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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LINKS
| Eric Weisstein's World of Mathematics, Repunit
P. De Geest, Repunits prime factors
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FORMULA
| a(n)=k where (10^k-1)/9 is not squarefree. - Ray Chandler (rayjchandler(AT)sbcglobal.net), Aug 10 2003
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CROSSREFS
| Cf. A000042, A004022, A046053, A084006, A087094.
Sequence in context: A062057 A015785 A141469 * A171081 A109661 A015798
Adjacent sequences: A046409 A046410 A046411 * A046413 A046414 A046415
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KEYWORD
| nonn,base
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AUTHOR
| Patrick De Geest (pdg(AT)worldofnumbers.com), Jul 15 1998.
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EXTENSIONS
| More terms from Ray Chandler (rayjchandler(AT)sbcglobal.net), Aug 10 2003
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