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A059452
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Safe primes (A005385) which are not Sophie Germain primes.
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23
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7, 47, 59, 107, 167, 227, 263, 347, 383, 467, 479, 503, 563, 587, 839, 863, 887, 983, 1187, 1283, 1307, 1319, 1367, 1487, 1523, 1619, 1823, 1907, 2027, 2099, 2207, 2447, 2579, 2879, 2999, 3119, 3167, 3203, 3467, 3947, 4007, 4079, 4127, 4139, 4259, 4283
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| A156659(a(n))*(1-A156660(a(n))) = 1. [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Feb 18 2009]
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LINKS
| C. K. Caldwell, Cunningham Chain
W. Roonguthai, Yves Gallot's Proth.exe and Cunningham Chains
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EXAMPLE
| 347 is here because 173 is a prime but 695 is not. Except for 7, these primes are congruent to 11 modulo 12. Terminal primes in complete Cunningham chains of first kind, i.e. the chains cannot be continued from these primes.
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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: A009241 A124837 A122731 * A141882 A067658 A044490
Adjacent sequences: A059449 A059450 A059451 * A059453 A059454 A059455
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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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EXTENSIONS
| Broken link updated by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 12 2010
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