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Search: id:A001770
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| A001770 |
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Numbers n such that 5*2^n - 1 is prime.
(Formerly M1087 N0415)
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+0
4
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| 2, 4, 8, 10, 12, 14, 18, 32, 48, 54, 72, 148, 184, 248, 270, 274, 420, 1340, 1438, 1522, 1638, 1754, 1884, 2014, 2170, 2548, 2622, 2652, 2704, 13510, 21738, 25624, 41934, 51478, 52540, 53230, 172300, 245728, 350028
(list; graph; listen)
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OFFSET
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1,1
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
H. C. Williams and C. R. Zarnke, Math. Comp., 22 (1968), 420-422.
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LINKS
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Y. Gallot, Proth.exe: Windows Program for Finding Large Primes
Wilfrid Keller, List of primes k.2^n - 1 for k < 300
Index entries for sequences of n such that k*2^n-1 (or k*2^n+1) is prime
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CROSSREFS
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Cf. A050522.
Cf. A002254, 5*2^n+1 is prime.
Sequence in context: A039011 A132190 A155037 this_sequence A032494 A125953 A047464
Adjacent sequences: A001767 A001768 A001769 this_sequence A001771 A001772 A001773
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KEYWORD
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nonn,nice,hard
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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More terms from Hugo Pfoertner (hugo(AT)pfoertner.org), Jun 23 2004
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