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Search: id:A108320
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| A108320 |
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Numbers n such that 609 * 10^n - 1 is prime. |
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+0
1
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| 1, 2, 3, 4, 5, 6, 12, 17, 43, 46, 50, 88, 110, 187, 472, 832, 834, 1034, 1311, 1700, 2756, 5470, 6124, 7404, 7891, 12010
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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These are "pimes," i.e. primes whose digits contain circles (0, 6, 8, 9) and they have all been certified. Primality proof for the largest: PFGW Version 1.2.0 for Windows [FFT v23.8] Primality testing 609*10^12010-1 [N+1, Brillhart-Lehmer-Selfridge] Running N+1 test using discriminant 11, base 1+sqrt(11) Running N+1 test using discriminant 11, base 2+sqrt(11) Calling Brillhart-Lehmer-Selfridge with factored part 69.88% 609*10^12010-1 is prime! (175.8270s+0.0024s)
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LINKS
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G. L. Honaker, Jr. and C. K. Caldwell, Prime Curios! 89
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EXAMPLE
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a(4)=4 because 609*10^4-1 = 6089999, a prime.
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CROSSREFS
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Cf. A053580.
Sequence in context: A032885 A023788 A032989 this_sequence A032941 A059460 A125141
Adjacent sequences: A108317 A108318 A108319 this_sequence A108321 A108322 A108323
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KEYWORD
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more,nonn
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AUTHOR
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Jason Earls (zevi_35711(AT)yahoo.com), Jun 30 2005
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