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Search: id:A074477
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| A074477 |
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Largest prime factor of 3^n - 1. |
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+0
3
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| 2, 2, 13, 5, 11, 13, 1093, 41, 757, 61, 3851, 73, 797161, 1093, 4561, 193, 34511, 757, 363889, 1181, 368089, 3851, 1001523179, 6481, 391151, 797161, 8209, 16493, 20381027, 4561, 4404047, 21523361, 2413941289, 34511, 2664097031, 530713
(list; graph; listen)
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OFFSET
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1,1
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LINKS
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S. S. Wagstaff, Jr., The Cunningham Project
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EXAMPLE
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3^7 - 1 = 2186 = 2*1093, so a(7) = 1093.
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PROGRAM
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(PARI) for(n=1, 40, v=factor(3^n-1); print1(v[matsize(v)[1], 1], ", "))
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CROSSREFS
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Cf. A074476 (largest prime factor of 3^n + 1), A005420 (largest prime factor of 2^n - 1), A074479 (largest prime factor of 5^n - 1).
Sequence in context: A032152 A032057 A130718 this_sequence A141575 A151352 A155915
Adjacent sequences: A074474 A074475 A074476 this_sequence A074478 A074479 A074480
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KEYWORD
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easy,nonn
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AUTHOR
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Rick L. Shepherd (rshepherd2(AT)hotmail.com), Aug 23 2002
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