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Search: id:A133857
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| A133857 |
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Numbers n such that (18^n - 1)/17 is prime. |
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1
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OFFSET
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1,1
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COMMENT
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a(2) = 25667 and a(3) = 28807 found by Henri Lifchitz 09/2007.
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REFERENCES
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H. Dubner, Generalized repunit primes, Math. Comp., 61 (1993), 927-930.
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LINKS
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Henri & Renaud Lifchitz, PRP Records.
Eric Weisstein's World of Mathematics, Repunit.
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EXAMPLE
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a(1) = A084740(18) = 2,
a(2) = A128164(18) = 25667.
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CROSSREFS
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Cf. A128164 = Least k>2 such that (n^k-1)/(n-1) is prime. Cf. A084740 = Least k such that (n^k-1)/(n-1) is prime. Cf. A126589 = Numbers n>1 such that prime of the form (n^k-1)/(n-1) does not exist for k>2.
Sequence in context: A123692 A132942 A131558 this_sequence A153912 A047076 A030462
Adjacent sequences: A133854 A133855 A133856 this_sequence A133858 A133859 A133860
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KEYWORD
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bref,hard,more,nonn
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AUTHOR
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Alexander Adamchuk (alex(AT)kolmogorov.com), Sep 28 2007
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