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A046418
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Repunit of length a(n) has exactly 7 prime factors (counted with multiplicity).
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2
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12, 20, 21, 22, 27, 35, 61, 65, 74, 82, 85, 141, 146, 177, 187, 194, 226, 299, 323, 329, 337
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listen;
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OFFSET
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1,1
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LINKS
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Eric Weisstein's World of Mathematics, Repunit
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MATHEMATICA
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Select[Range[300], PrimeOmega[FromDigits[PadRight[{}, #, 1]]]==7&] (* Harvey P. Dale, Feb 04 2019 *)
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CROSSREFS
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KEYWORD
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nonn,base,more,changed
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AUTHOR
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EXTENSIONS
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Changed offset to 1, a(18) added by Ray Chandler, Apr 23 2017
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STATUS
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approved
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