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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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3
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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; refs; listen; history; internal format)
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OFFSET
| 1,1
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REFERENCES
| N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
H. C. Williams and C. R. Zarnke, Math. Comp., 22 (1968), 420-422.
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LINKS
| 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
| Cf. A050522.
Cf. A002254, 5*2^n+1 is prime.
Sequence in context: A039011 A132190 A155037 * A032494 A125953 A047464
Adjacent sequences: A001767 A001768 A001769 * A001771 A001772 A001773
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KEYWORD
| nonn,nice,hard
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| More terms from Hugo Pfoertner (hugo(AT)pfoertner.org), Jun 23 2004
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