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Search: id:A075705
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| A075705 |
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Safe primes (A005385) (p and (p-1)/2 are primes) such that 6*p+1 is also prime. |
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+0
1
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| 5, 7, 11, 23, 47, 83, 107, 263, 347, 467, 503, 863, 887, 1283, 1487, 1823, 1907, 2027, 2063, 2447, 2903
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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47 is prime, so is (47-1)/2=23 and also 6*47+1=283; 83 is a prime, (83-1)/2=41 and 6*83+1=499, ...
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MAPLE
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ts_sg_var_pras := proc(nmax) local i, tren, atek; tren := 0: for i from 1 to nmax do atek := numtheory[safeprime](i): if (atek > tren) then if (isprime(atek)='true' and isprime(6*atek+1)='true') then tren := atek: fi; fi; od; end: seq(ts_sg_var_pras(i), i=1..3000);
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CROSSREFS
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Cf. A005384, A005385, A059455, A007693.
Sequence in context: A090810 A092307 A005385 this_sequence A141305 A067289 A036491
Adjacent sequences: A075702 A075703 A075704 this_sequence A075706 A075707 A075708
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KEYWORD
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nonn,more
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AUTHOR
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Jani Melik (jani_melik(AT)hotmail.com), Oct 02 2002
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