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Search: id:A157347
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| A157347 |
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Products of 3 distinct not-Sophie Germain primes. |
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+0
8
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| 1547, 1729, 2261, 2821, 3367, 3689, 3913, 4123, 4199, 4277, 4403, 4921, 5117, 5369, 5551, 5593, 5719, 6097, 6251, 6461, 6643, 6851, 7021, 7189, 7259, 7657, 7847, 7973, 8029, 8113, 8177, 8449, 8687, 8827, 8911, 9139, 9191, 9331, 9373, 9401, 9443, 9503
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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1547=7*13*17; 7,13 and 17 are not-Sophie Germain primes,...
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MATHEMATICA
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lst={}; Do[If[Plus@@Last/@FactorInteger[n]==3, a=Length[First/@FactorInteger[n]]; If[a==3, b=First/@FactorInteger[n]; c=b[[1]]; d=b[[2]]; e=b[[3]]; If[ !PrimeQ[2*c+1]&&!PrimeQ[2*d+1]&&!PrimeQ[2*e+1], AppendTo[lst, n]]]], {n, 8!}]; lst
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PROGRAM
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(MAGMA) S:=[ p: p in PrimesUpTo(120) | not IsPrime(2*p+1) ]; T:=[ q: a, b, c in S | a lt b and b lt c and q lt 10000 where q is a*b*c ]; Sort(~T); T; [From Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Apr 11 2009]
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CROSSREFS
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Cf. A001358, A005384, A111206, A157342, A006881, A157344, A157345, A007304, A157346
Sequence in context: A133560 A038009 A090209 this_sequence A020408 A022222 A166606
Adjacent sequences: A157344 A157345 A157346 this_sequence A157348 A157349 A157350
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KEYWORD
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nonn
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AUTHOR
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Vladimir Orlovsky (4vladimir(AT)gmail.com), Feb 27 2009
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EXTENSIONS
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Entries verified by Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Apr 11 2009
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