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Search: id:A046412
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A046412 Repunits of length a(n) without having distinct prime factors. +0
2
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; listen)
OFFSET

0,1

LINKS

Eric Weisstein's World of Mathematics, Repunit

P. De Geest, Repunits prime factors

FORMULA

a(n)=k where (10^k-1)/9 is not square-free. - Ray Chandler (rayjchandler(AT)sbcglobal.net), Aug 10 2003

CROSSREFS

Cf. A000042, A004022, A046053, A084006, A087094.

Adjacent sequences: A046409 A046410 A046411 this_sequence A046413 A046414 A046415

Sequence in context: A092457 A062057 A015785 this_sequence A109661 A015798 A028494

KEYWORD

nonn,base

AUTHOR

Patrick De Geest (pdg(AT)worldofnumbers.com), Jul 15 1998.

EXTENSIONS

More terms from Ray Chandler (rayjchandler(AT)sbcglobal.net), Aug 10 2003

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Last modified May 16 23:01 EDT 2008. Contains 139884 sequences.


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