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A023270
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Primes that remain prime through 2 iterations of function f(x) = 10x + 9.
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3
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5, 13, 19, 23, 47, 61, 103, 127, 139, 233, 257, 293, 331, 433, 463, 491, 499, 547, 593, 701, 859, 967, 1009, 1013, 1049, 1223, 1321, 1399, 1493, 1567, 1723, 1811, 1867, 1889, 1997, 2039, 2063, 2087, 2137, 2203, 2267, 2273, 2309, 2423, 2437, 2441, 2609, 2633
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OFFSET
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1,1
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COMMENTS
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Primes p such that 10*p+9 and 100*p+99 are also primes. - Vincenzo Librandi, Aug 04 2010
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LINKS
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MATHEMATICA
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Select[Prime[Range[400]], AllTrue[NestList[10#+9&, #, 2], PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Jun 05 2015 *)
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PROG
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(Magma) [n: n in [1..100000] | IsPrime(n) and IsPrime(10*n+9) and IsPrime(100*n+99)] // Vincenzo Librandi, Aug 04 2010
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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