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Search: id:A135978
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| A135978 |
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Prime numbers n such that Mersenne composite 2^n-1 has exactly 2 prime factors. |
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+0
5
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| 11, 23, 37, 41, 59, 67, 83, 97, 101, 103, 109, 131, 137, 139, 149, 167
(list; graph; listen)
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OFFSET
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1,1
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MATHEMATICA
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k = {}; Do[If[ ! PrimeQ[2^Prime[n] - 1], c = FactorInteger[2^Prime[n] - 1]; d = Length[c]; If[d == 2, AppendTo[k, Prime[n]]]], {n, 1, 40}]; k
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CROSSREFS
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Cf. A000225, A065341, A054723, A134852, A135975, A135976, A135977, A135978.
Sequence in context: A139793 A101859 A079664 this_sequence A139493 A077345 A130282
Adjacent sequences: A135975 A135976 A135977 this_sequence A135979 A135980 A135981
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KEYWORD
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nonn
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AUTHOR
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Artur Jasinski (grafix(AT)csl.pl), Dec 09 2007
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