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A023245
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Numbers n such that n remains prime through 2 iterations of function f(x) = 2x + 9.
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0
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5, 11, 19, 31, 59, 61, 71, 101, 109, 151, 179, 239, 241, 269, 281, 389, 409, 439, 449, 521, 571, 641, 659, 719, 829, 911, 971, 1051, 1061, 1181, 1201, 1229, 1319, 1361, 1439, 1579, 1669, 1699, 1741, 1831, 1949, 2269, 2341, 2371, 2521, 2549, 2579, 2609, 2671
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| n, 2*n+9, 4*n+27 are primes. [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Aug 04 2010]
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MATHEMATICA
| Select[Prime[Range[500]], And@@PrimeQ[Rest[NestList[2#+9&, #, 2]]]&] (* From Harvey P. Dale, Mar 23 2011 *)
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PROG
| (MAGMA) [n: n in [0..100000] | IsPrime(n) and IsPrime(2*n+9) and IsPrime(4*n+27)] [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Aug 04 2010]
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CROSSREFS
| Sequence in context: A075322 A079850 A065995 * A125003 A062718 A105914
Adjacent sequences: A023242 A023243 A023244 * A023246 A023247 A023248
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KEYWORD
| nonn
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AUTHOR
| David W. Wilson (davidwwilson(AT)comcast.net)
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