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A059453
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Sophie Germain primes (A005384) which are not safe primes (A005385).
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9
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2, 3, 29, 41, 53, 89, 113, 131, 173, 191, 233, 239, 251, 281, 293, 419, 431, 443, 491, 509, 593, 641, 653, 659, 683, 743, 761, 809, 911, 953, 1013, 1031, 1049, 1103, 1223, 1229, 1289, 1409, 1451, 1481, 1499, 1511, 1559, 1583, 1601, 1733, 1811, 1889, 1901
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| A156660(a(n))*(1-A156659(a(n))) = 1. [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Feb 18 2009]
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LINKS
| C. K. Caldwell, Cunningham Chains
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EXAMPLE
| 89 is here because (89-1)/2=44 is not prime, but 2.89+1=179 is prime. Except for 2 and 3 these primes are congruent to 5 or 11 modulo 12. Introducing terms of Cunningham chains of first kind.
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MATHEMATICA
| lst={}; Do[p=Prime[n]; If[ !PrimeQ[(p-1)/2], If[PrimeQ[2*p+1], AppendTo[lst, p]]], {n, 6!}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Jun 24 2009]
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CROSSREFS
| Cf. A005384, A005385, A053176, A059452-A059456, A007700, A005602, A023272, A023302, A023330.
Sequence in context: A041193 A042335 A141192 * A137472 A065932 A143882
Adjacent sequences: A059450 A059451 A059452 * A059454 A059455 A059456
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), Feb 02 2001
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