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Search: id:A085724
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| 4, 9, 11, 23, 37, 41, 49, 59, 67, 83, 97, 101, 103, 109, 131, 137, 139, 149, 167, 197, 199, 227, 241, 269, 271, 281, 293, 347, 373, 379, 421, 457, 487, 523, 727, 809, 881, 971, 983, 997
(list; graph; listen)
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OFFSET
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1,1
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REFERENCES
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J. Earls, Mathematical Bliss, Pleroma Publications, 2009, pages 56-60. ASIN: B002ACVZ6O [From Jason Earls (zevi_35711(AT)yahoo.com), Nov 22 2009]
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LINKS
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S. S. Wagstaff, Jr., The Cunningham Project
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EXAMPLE
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11 is a member because 2^11-1=23*89
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MATHEMATICA
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SemiPrimeQ[n_]:=(n>1) && (2==Plus@@(Transpose[FactorInteger[n]][[2]])); Select[Range[100], SemiPrimeQ[2^#-1]&] (Noe)
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CROSSREFS
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Cf. A092558, A092559, A092561 and A092562.
Sequence in context: A162188 A141365 A002641 this_sequence A106854 A099458 A069219
Adjacent sequences: A085721 A085722 A085723 this_sequence A085725 A085726 A085727
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KEYWORD
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nonn,new
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AUTHOR
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Jason Earls (zevi_35711(AT)yahoo.com), Jul 20 2003
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EXTENSIONS
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More terms from Zak Seidov (zakseidov(AT)yahoo.com), Feb 27 2004
More terms from Cunningham project, Mar 23 2004
More terms from the Cunningham project sent by Robert G. Wilson v and T. D. Noe (noe(AT)sspectra.com), Feb 22 2006
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