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A050586
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Numbers n such that 121*2^n-1 is a prime.
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1
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1, 3, 21, 27, 37, 43, 91, 117, 141, 163, 373, 421, 1581, 2035, 10701, 18931, 21307, 51195, 64579, 156541, 302097, 334257, 368059, 383061, 410131, 494317, 541621, 990219, 1039965, 1526097, 1589157, 1695499, 1954243, 2033941
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,2
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COMMENTS
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4553899 is also in the sequence. - Felix Fröhlich, Jul 04 2014
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LINKS
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Table of n, a(n) for n=1..34.
Author?, 12121 Search [Archived at Wayback Machine].
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
Kosmaj, Riesel list k<300.
PrimeGrid, Announcement of n=4553899 - Felix Fröhlich, Jul 04 2014
Index entries for sequences of n such that k*2^n-1 (or k*2^n+1) is a prime
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MATHEMATICA
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Select[Range[2500], PrimeQ[121*2^# - 1] &] (* Michael De Vlieger, Dec 10 2020 *)
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CROSSREFS
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Cf. A032410.
Sequence in context: A067233 A007648 A273481 * A074217 A350247 A062219
Adjacent sequences: A050583 A050584 A050585 * A050587 A050588 A050589
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KEYWORD
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hard,nonn
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AUTHOR
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N. J. A. Sloane, Dec 29 1999
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EXTENSIONS
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More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
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STATUS
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approved
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