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 A157344 Semiprimes that are the product of two distinct Sophie Germain primes. 11
 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; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS 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, ... LINKS G. C. Greubel, Table of n, a(n) for n = 1..5000 MATHEMATICA 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 nn=100; With[{sgp=Select[Prime[Range[nn]], PrimeQ[2#+1]&]}, Take[ Union[ Select[ Times @@@ Subsets[sgp, {2}], PrimeOmega[#]==2&]], nn]] (* Harvey P. Dale, Nov 22 2012 *) CROSSREFS Cf. A001358, A005384, A111206, A157342, A006881. Sequence in context: A022949 A049694 A285766 * A093773 A088708 A174872 Adjacent sequences:  A157341 A157342 A157343 * A157345 A157346 A157347 KEYWORD nonn AUTHOR Vladimir Joseph Stephan Orlovsky, Feb 27 2009 STATUS approved

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Last modified October 17 16:51 EDT 2019. Contains 328120 sequences. (Running on oeis4.)