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Search: id:A002238
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| A002238 |
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Numbers n such that 21*2^n-1 is prime.
(Formerly M0825 N0314)
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+0
1
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| 1, 2, 3, 7, 10, 13, 18, 27, 37, 51, 74, 157, 271, 458, 530, 891, 1723, 1793, 1849, 1986, 2191, 2869, 4993, 7777, 11730, 15313, 29171, 35899, 36227, 71570, 199219, 233914, 297499, 332523, 348547, 538657, 986130, 999599
(list; graph; listen)
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OFFSET
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1,2
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REFERENCES
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H. Riesel, Lucasian criteria for the primality of N=h.2^n-1, Math. Comp., 23 (1969), 869-875.
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).
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LINKS
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Ray Ballinger and Wilfrid Keller, List of primes k.2^n + 1 for k < 300
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
Kosmaj, Riesel list k<300.
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CROSSREFS
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Cf. A032360, 21*2^n+1 is prime.
Sequence in context: A102808 A140512 A101956 this_sequence A002255 A088163 A048448
Adjacent sequences: A002235 A002236 A002237 this_sequence A002239 A002240 A002241
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KEYWORD
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hard,nonn
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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 22 2004
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
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