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Search: id:A157357
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| A157357 |
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Products of 3 distinct triple-safe primes. |
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+0
4
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OFFSET
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1,1
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COMMENT
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777239=11*23*47; 11,23 and 47 are triple-safe prime numbers,...
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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[cx=(c-1)/2]&&PrimeQ[cy=(cx-1)/2]&&PrimeQ[(cy-1)/2]&&PrimeQ[dx=(d-1)/2]\ &&PrimeQ[dy=(dx-1)/2]&&PrimeQ[(dy-1)/2]&&PrimeQ[ex=(e-1)/2]&&PrimeQ[ey=(ex-1)/2]\ &&PrimeQ[(ey-1)/2], AppendTo[lst, n]]]], {n, 9!, 11!}]; lst
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CROSSREFS
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Cf. A001358, A005384, A005385, A006881, A007304, A066179, A111206, A157342, A157344, A157345, A157346, A157347, A157352, A157353, A157354, A157355, A157356
Sequence in context: A023348 A089007 A145687 this_sequence A146953 A157993 A115175
Adjacent sequences: A157354 A157355 A157356 this_sequence A157358 A157359 A157360
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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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