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Search: id:A099006
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| A099006 |
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Numbers n such that 2*10^n + 5*R_n + 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n. |
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+0
2
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| 2, 3, 26, 27, 45, 62, 147, 1277, 1665, 1979, 2970
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Also numbers n such that (23*10^n+13)/9 is prime.
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LINKS
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Makoto Kamada, Factorizations of 255...557.
Index entries for primes involving repunits.
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EXAMPLE
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n = 2, 3, 26, 27 are members since 257, 2557, 255555555555555555555555557 and
2555555555555555555555555557 are primes.
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MATHEMATICA
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Do[ If[ PrimeQ[(23*10^n + 13)/9], Print[n]], {n, 0, 10000}]
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CROSSREFS
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Sequence in context: A002748 A056004 A032812 this_sequence A041659 A042043 A056722
Adjacent sequences: A099003 A099004 A099005 this_sequence A099007 A099008 A099009
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KEYWORD
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more,nonn
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AUTHOR
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Julien Peter Benney (jpbenney(AT)ftml.net), Nov 07 2004
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EXTENSIONS
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a(8), a(9), a(10) & a(11) from Sam Handler (sam_5_5_5_0(AT)yahoo.com), Nov 17 2004
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