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A032360 Numbers n such that 21*2^n+1 is prime. 1
1, 4, 5, 7, 9, 12, 16, 17, 41, 124, 128, 129, 187, 209, 276, 313, 397, 899, 1532, 1613, 1969, 2245, 2733, 4585, 4644, 6712, 6981, 13344, 17524, 27124, 29769, 47337, 55828, 91008, 94801, 164901, 179457, 191337, 200568, 220992, 686632, 856865, 1022168, 1240067, 1421741, 1830919 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..46.

Ray Ballinger, Proth Search Page

Ray Ballinger and Wilfrid Keller, List of primes k.2^n + 1 for k < 300

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

PROG

(PARI) is(n)=ispseudoprime(21*2^n+1) \\ Charles R Greathouse IV, Jun 06 2017

CROSSREFS

Sequence in context: A286050 A047493 A285307 * A117150 A239276 A284132

Adjacent sequences:  A032357 A032358 A032359 * A032361 A032362 A032363

KEYWORD

nonn,hard

AUTHOR

James R. Buddenhagen

EXTENSIONS

More terms from Hugo Pfoertner, Jun 20 2003

Added more terms (from http://web.archive.org/web/20161028080239/http://www.prothsearch.net/riesel.html), Joerg Arndt, Apr 07 2013

STATUS

approved

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Last modified September 23 17:50 EDT 2017. Contains 292363 sequences.