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Search: id:A157344
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| A157344 |
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Semiprimes that are the product of two distinct Sophie Germain primes. |
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+0
11
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| 6, 10, 15, 22, 33, 46, 55, 58, 69, 82, 87, 106, 115, 123, 145, 159, 166, 178, 205, 226, 249, 253, 262, 265, 267, 319, 339, 346, 358, 382, 393, 415, 445, 451, 466, 478, 502, 519, 537, 562, 565, 573, 583, 586, 655, 667, 699, 717, 718, 753, 838, 843, 862, 865
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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6=2*3; 2 and 3 are Sophie Germain primes, 10=2*5; 2 and 5 are Sophie Germain primes, 15=3*5; 3 and 5 are Sophie Germain primes,...
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MATHEMATICA
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lst={}; Do[If[Plus@@Last/@FactorInteger[n]==2, a=Length[First/@FactorInteger[n]]; If[a==2, b=First/@FactorInteger[n]; c=b[[1]]; d=b[[2]]; If[PrimeQ[2*c+1]&&PrimeQ[2*d+1], AppendTo[lst, n]]]], {n, 7!}]; lst
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CROSSREFS
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Cf. A001358, A005384, A111206, A157342, A006881
Sequence in context: A099981 A022949 A049694 this_sequence A093773 A088708 A020159
Adjacent sequences: A157341 A157342 A157343 this_sequence A157345 A157346 A157347
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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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