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A023330
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Numbers n such that n remains prime through 5 iterations of function f(x) = 2x + 1.
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33
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89, 63419, 127139, 405269, 810809, 1069199, 1122659, 1178609, 1333889, 1598699, 1806089, 1958249, 2164229, 2245319, 2329469, 2606069, 2848949, 3241289, 3339989, 3784199, 3962039, 4088879, 4328459, 4444829, 4658939, 4664249, 4894889, 4897709
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| n, 2*n+1, 4*n+3, 8*n+7, 16*n+15 and 32*n+31 are primes. [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Aug 04 2010]
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MATHEMATICA
| Select[Prime[Range[10^5]], PrimeQ[a1=2*#+1]&&PrimeQ[a2=2*a1+1]&&PrimeQ[a3=2*a2+1]&&PrimeQ[a4=2*a3+1]&&PrimeQ[a5=2*a4+1] &] (from Vladimir Orlovsky (4vladimir(AT)gmail.com), May 01 2008)
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PROG
| (MAGMA) [n: n in [1..5000000] | IsPrime(n) and IsPrime(2*n+1) and IsPrime(4*n+3) and IsPrime(8*n+7) and IsPrime(16*n+15) and IsPrime(32*n+31)] [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Aug 04 2010]
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CROSSREFS
| Cf. (A005384 and A005385), A007700, A023272, A023302, A057331, A005602.
Sequence in context: A174758 A181681 A167398 * A059766 A033513 A128872
Adjacent sequences: A023327 A023328 A023329 * A023331 A023332 A023333
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KEYWORD
| nonn
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AUTHOR
| David W. Wilson (davidwwilson(AT)comcast.net)
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