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A023302
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Numbers n such that n remains prime through 4 iterations of function f(x) = 2x + 1.
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31
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2, 89, 179, 53639, 53849, 61409, 63419, 66749, 126839, 127139, 143609, 167729, 186149, 206369, 254279, 268049, 296099, 340919, 405269, 422069, 446609, 539009, 594449, 607319, 658349, 671249, 725009, 775949, 810539, 810809, 812849, 819509
(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 and 16*n+15 are primes. [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Aug 04 2010]
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MATHEMATICA
| Select[Prime[Range[10^4*4]], PrimeQ[a1=2*#+1]&&PrimeQ[a2=2*a1+1]&&PrimeQ[a3=2*a2+1]&&PrimeQ[a4=2*a3+1] &] (from Vladimir Orlovsky (4vladimir(AT)gmail.com), May 01 2008)
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PROG
| (MAGMA) [n: n in [1..1200000] | IsPrime(n) and IsPrime(2*n+1) and IsPrime(4*n+3) and IsPrime(8*n+7) and IsPrime(16*n+15)] [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Aug 04 2010]
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CROSSREFS
| Cf. (A005384 and A005385), A007700, A023272, A023330, A057331, A005602.
Sequence in context: A105268 A139881 A161676 * A041967 A024239 A076532
Adjacent sequences: A023299 A023300 A023301 * A023303 A023304 A023305
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KEYWORD
| nonn
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AUTHOR
| David W. Wilson (davidwwilson(AT)comcast.net)
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